91990979 has 4 divisors (see below), whose sum is σ = 92662584. Its totient is φ = 91319376.

The previous prime is 91990973. The next prime is 91990999. The reversal of 91990979 is 97909919.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-91990979 is a prime.

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 91990979.

It is not an unprimeable number, because it can be changed into a prime (91990973) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 335597 + ... + 335870.

It is an arithmetic number, because the mean of its divisors is an integer number (23165646).

Almost surely, 2^91990979 is an apocalyptic number.

91990979 is a deficient number, since it is larger than the sum of its proper divisors (671605).

91990979 is a wasteful number, since it uses less digits than its factorization.

91990979 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 671604.

The product of its (nonzero) digits is 413343, while the sum is 53.

The square root of 91990979 is about 9591.1927829650. The cubic root of 91990979 is about 451.4209879860.

The spelling of 91990979 in words is "ninety-one million, nine hundred ninety thousand, nine hundred seventy-nine".