91815983 has 4 divisors (see below), whose sum is σ = 104932560. Its totient is φ = 78699408.

The previous prime is 91815979. The next prime is 91815989. The reversal of 91815983 is 38951819.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 91815983 - 2² = 91815979 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 (91815989) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6558278 + ... + 6558291.

It is an arithmetic number, because the mean of its divisors is an integer number (26233140).

Almost surely, 2^91815983 is an apocalyptic number.

91815983 is a deficient number, since it is larger than the sum of its proper divisors (13116577).

91815983 is a wasteful number, since it uses less digits than its factorization.

91815983 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13116576.

The product of its digits is 77760, while the sum is 44.

The square root of 91815983 is about 9582.0656958716. The cubic root of 91815983 is about 451.1345576807.

The spelling of 91815983 in words is "ninety-one million, eight hundred fifteen thousand, nine hundred eighty-three".