91990787 has 6 divisors (see below), whose sum is σ = 107009748. Its totient is φ = 78849204.

The previous prime is 91990783. The next prime is 91990807. The reversal of 91990787 is 78709919.

It is not a de Polignac number, because 91990787 - 2² = 91990783 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (91990783) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 938633 + ... + 938730.

It is an arithmetic number, because the mean of its divisors is an integer number (17834958).

Almost surely, 2^91990787 is an apocalyptic number.

91990787 is a deficient number, since it is larger than the sum of its proper divisors (15018961).

91990787 is a wasteful number, since it uses less digits than its factorization.

91990787 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1877377 (or 1877370 counting only the distinct ones).

The product of its (nonzero) digits is 285768, while the sum is 50.

The square root of 91990787 is about 9591.1827737772. The cubic root of 91990787 is about 451.4206739230.

The spelling of 91990787 in words is "ninety-one million, nine hundred ninety thousand, seven hundred eighty-seven".