91915997 has 2 divisors, whose sum is σ = 91915998. Its totient is φ = 91915996.

The previous prime is 91915987. The next prime is 91916009. The reversal of 91915997 is 79951919.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 87871876 + 4044121 = 9374^2 + 2011^2 .

It is a cyclic number.

It is not a de Polignac number, because 91915997 - 2⁸ = 91915741 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (91915927) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45957998 + 45957999.

It is an arithmetic number, because the mean of its divisors is an integer number (45957999).

Almost surely, 2^91915997 is an apocalyptic number.

It is an amenable number.

91915997 is a deficient number, since it is larger than the sum of its proper divisors (1).

91915997 is an equidigital number, since it uses as much as digits as its factorization.

91915997 is an evil number, because the sum of its binary digits is even.

The product of its digits is 229635, while the sum is 50.

The square root of 91915997 is about 9587.2830875071. The cubic root of 91915997 is about 451.2983033137.

The spelling of 91915997 in words is "ninety-one million, nine hundred fifteen thousand, nine hundred ninety-seven".