91431257 has 2 divisors, whose sum is σ = 91431258. Its totient is φ = 91431256.

The previous prime is 91431209. The next prime is 91431283. The reversal of 91431257 is 75213419.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 52693081 + 38738176 = 7259^2 + 6224^2 .

It is a cyclic number.

It is not a de Polignac number, because 91431257 - 2²⁰ = 90382681 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (91431157) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45715628 + 45715629.

It is an arithmetic number, because the mean of its divisors is an integer number (45715629).

Almost surely, 2^91431257 is an apocalyptic number.

It is an amenable number.

91431257 is a deficient number, since it is larger than the sum of its proper divisors (1).

91431257 is an equidigital number, since it uses as much as digits as its factorization.

91431257 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 7560, while the sum is 32.

The square root of 91431257 is about 9561.9693055353. The cubic root of 91431257 is about 450.5035630372.

The spelling of 91431257 in words is "ninety-one million, four hundred thirty-one thousand, two hundred fifty-seven".