91915819840 has 56 divisors (see below), whose sum is σ = 235711060200. Its totient is φ = 33938147328.

The previous prime is 91915819817. The next prime is 91915819867. The reversal of 91915819840 is 4891851919.

It can be written as a sum of positive squares in 4 ways, for example, as 16519446784 + 75396373056 = 128528^2 + 274584^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 11043415 + ... + 11051734.

It is an arithmetic number, because the mean of its divisors is an integer number (4209126075).

Almost surely, 2^91915819840 is an apocalyptic number.

It is an amenable number.

91915819840 is an abundant number, since it is smaller than the sum of its proper divisors (143795240360).

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

91915819840 is a wasteful number, since it uses less digits than its factorization.

91915819840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22095179 (or 22095169 counting only the distinct ones).

The product of its (nonzero) digits is 933120, while the sum is 55.

The spelling of 91915819840 in words is "ninety-one billion, nine hundred fifteen million, eight hundred nineteen thousand, eight hundred forty".