91631820 has 48 divisors (see below), whose sum is σ = 293223168. Its totient is φ = 20944320.

The previous prime is 91631809. The next prime is 91631849. The reversal of 91631820 is 2813619.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 108666 + ... + 109505.

It is an arithmetic number, because the mean of its divisors is an integer number (6108816).

Almost surely, 2^91631820 is an apocalyptic number.

It is an amenable number.

91631820 is an abundant number, since it is smaller than the sum of its proper divisors (201591348).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

91631820 is a wasteful number, since it uses less digits than its factorization.

91631820 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 218190 (or 218188 counting only the distinct ones).

The product of its (nonzero) digits is 2592, while the sum is 30.

The square root of 91631820 is about 9572.4510967672. The cubic root of 91631820 is about 450.8327296795.

The spelling of 91631820 in words is "ninety-one million, six hundred thirty-one thousand, eight hundred twenty".