# 290 (number)

(Redirected from 291 (number))

290 (two hundred [and] ninety) is the natural number following 289 and preceding 291.

 ← 289 290 291 →
Cardinaltwo hundred ninety
Ordinal290th
(two hundred ninetieth)
Factorization2 × 5 × 29
Greek numeralΣϞ´
Roman numeralCCXC
Binary1001000102
Ternary1012023
Senary12026
Octal4428
Duodecimal20212

## In mathematics

The product of three primes, 290 is a sphenic number, and the sum of four consecutive primes (67 + 71 + 73 + 79). The sum of the squares of the divisors of 17 is 290.

Not only is it a nontotient and a noncototient, it is also an untouchable number.

290 is the 16th member of the Mian–Chowla sequence; it can not be obtained as the sum of any two previous terms in the sequence.

## Integers from 291 to 299

### 291

291 = 3·97, a semiprime, floor(3^14/2^14) (sequence A002379 in the OEIS).

### 292

292 = 22·73, a noncototient, untouchable number. The continued fraction representation of $\pi$  is [3; 7, 15, 1, 292, 1, 1, 1, 2...]; the convergent obtained by truncating before the surprisingly large term 292 yields the excellent rational approximation 355/113 to $\pi$ , repdigit in base 8 (444).

### 293

293 is prime, Sophie Germain prime, Chen prime, Irregular prime, Eisenstein prime with no imaginary part, and a strictly non-palindromic number.

### 294

294 = 2·3·72, the number of rooted trees with 28 vertices in which vertices at the same level have the same degree (sequence A003238 in the OEIS).

### 295

295 = 5·59, a centered tetrahedral number

### 296

296 = 23·37, a refactorable number, unique period in base 2, the number of regions formed by drawing the line segments connecting any two of the 12 perimeter points of an 2 times 4 grid of squares (illustration) (sequence A331452 in the OEIS), and the number of surface points on a 83 cube.

### 297

297 = 33·11, the number of integer partitions of 17, a decagonal number, and a Kaprekar number

### 298

298 = 2·149, is nontotient, noncototient, and the number of polynomial symmetric functions of matrix of order 6 under separate row and column permutations

### 299

299 = 13·23, a highly cototient number, a self number, and the twelfth cake number