91568991 has 16 divisors (see below), whose sum is σ = 124445408. Its totient is φ = 59875200.

The previous prime is 91568977. The next prime is 91569007. The reversal of 91568991 is 19986519.

It is not a de Polignac number, because 91568991 - 2⁵ = 91568959 is a prime.

It is a super-2 number, since 2×91568991² = 16769760225516162, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 91568991.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (91568941) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 120585 + ... + 121341.

It is an arithmetic number, because the mean of its divisors is an integer number (7777838).

Almost surely, 2^91568991 is an apocalyptic number.

91568991 is a deficient number, since it is larger than the sum of its proper divisors (32876417).

91568991 is a wasteful number, since it uses less digits than its factorization.

91568991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1482.

The product of its digits is 174960, while the sum is 48.

The square root of 91568991 is about 9569.1687726782. The cubic root of 91568991 is about 450.7296656057.

The spelling of 91568991 in words is "ninety-one million, five hundred sixty-eight thousand, nine hundred ninety-one".