91215387900 has 720 divisors, whose sum is σ = 369550680576. Its totient is φ = 18947934720.

The previous prime is 91215387871. The next prime is 91215387917. The reversal of 91215387900 is 978351219.

91215387900 is a `hidden beast` number, since 9 + 1 + 21 + 538 + 7 + 90 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 239 ways as a sum of consecutive naturals, for example, 49384777 + ... + 49386623.

Almost surely, 2^91215387900 is an apocalyptic number.

91215387900 is a gapful number since it is divisible by the number (90) 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 91215387900, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (184775340288).

91215387900 is an abundant number, since it is smaller than the sum of its proper divisors (278335292676).

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

91215387900 is a wasteful number, since it uses less digits than its factorization.

91215387900 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1960 (or 1944 counting only the distinct ones).

The product of its (nonzero) digits is 136080, while the sum is 45.

The spelling of 91215387900 in words is "ninety-one billion, two hundred fifteen million, three hundred eighty-seven thousand, nine hundred".