91999957 has 8 divisors (see below), whose sum is σ = 110676800. Its totient is φ = 74706624.

The previous prime is 91999951. The next prime is 91999961. The reversal of 91999957 is 75999919.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 91999957 - 2⁷ = 91999829 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (91999951) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 345732 + ... + 345997.

It is an arithmetic number, because the mean of its divisors is an integer number (13834600).

Almost surely, 2^91999957 is an apocalyptic number.

It is an amenable number.

91999957 is a deficient number, since it is larger than the sum of its proper divisors (18676843).

91999957 is a wasteful number, since it uses less digits than its factorization.

91999957 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 691755.

The product of its digits is 2066715, while the sum is 58.

The square root of 91999957 is about 9591.6608050952. The cubic root of 91999957 is about 451.4356732150.

The spelling of 91999957 in words is "ninety-one million, nine hundred ninety-nine thousand, nine hundred fifty-seven".