91978012 has 48 divisors (see below), whose sum is σ = 202083840. Its totient is φ = 35716032.

The previous prime is 91978009. The next prime is 91978021. The reversal of 91978012 is 21087919.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 8478 + ... + 15994.

It is an arithmetic number, because the mean of its divisors is an integer number (4210080).

Almost surely, 2^91978012 is an apocalyptic number.

91978012 is a gapful number since it is divisible by the number (92) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 91978012, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (101041920).

91978012 is an abundant number, since it is smaller than the sum of its proper divisors (110105828).

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

91978012 is a wasteful number, since it uses less digits than its factorization.

91978012 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7570 (or 7568 counting only the distinct ones).

The product of its (nonzero) digits is 9072, while the sum is 37.

The square root of 91978012 is about 9590.5167743975. The cubic root of 91978012 is about 451.3997763010.

The spelling of 91978012 in words is "ninety-one million, nine hundred seventy-eight thousand, twelve".