261031657 has 2 divisors, whose sum is σ = 261031658. Its totient is φ = 261031656.

The previous prime is 261031643. The next prime is 261031691. The reversal of 261031657 is 756130162.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 229492201 + 31539456 = 15149^2 + 5616^2 .

It is a cyclic number.

It is not a de Polignac number, because 261031657 - 2²³ = 252643049 is a prime.

It is not a weakly prime, because it can be changed into another prime (261031607) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130515828 + 130515829.

It is an arithmetic number, because the mean of its divisors is an integer number (130515829).

Almost surely, 2^261031657 is an apocalyptic number.

It is an amenable number.

261031657 is a deficient number, since it is larger than the sum of its proper divisors (1).

261031657 is an equidigital number, since it uses as much as digits as its factorization.

261031657 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 7560, while the sum is 31.

The square root of 261031657 is about 16156.4741512497. The cubic root of 261031657 is about 639.0934895536.

The spelling of 261031657 in words is "two hundred sixty-one million, thirty-one thousand, six hundred fifty-seven".