91157321 has 2 divisors, whose sum is σ = 91157322. Its totient is φ = 91157320.

The previous prime is 91157317. The next prime is 91157351. The reversal of 91157321 is 12375119.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 82537225 + 8620096 = 9085^2 + 2936^2 .

It is a cyclic number.

It is not a de Polignac number, because 91157321 - 2² = 91157317 is a prime.

It is not a weakly prime, because it can be changed into another prime (91157351) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45578660 + 45578661.

It is an arithmetic number, because the mean of its divisors is an integer number (45578661).

Almost surely, 2^91157321 is an apocalyptic number.

It is an amenable number.

91157321 is a deficient number, since it is larger than the sum of its proper divisors (1).

91157321 is an equidigital number, since it uses as much as digits as its factorization.

91157321 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1890, while the sum is 29.

The square root of 91157321 is about 9547.6343143210. The cubic root of 91157321 is about 450.0531970032.

The spelling of 91157321 in words is "ninety-one million, one hundred fifty-seven thousand, three hundred twenty-one".