81693937920 has 1152 divisors, whose sum is σ = 334554071040. Its totient is φ = 16562257920.

The previous prime is 81693937909. The next prime is 81693937943. The reversal of 81693937920 is 2973939618.

It is an unprimeable number.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 1034100441 + ... + 1034100519.

It is an arithmetic number, because the mean of its divisors is an integer number (290411520).

Almost surely, 2^81693937920 is an apocalyptic number.

81693937920 is a gapful number since it is divisible by the number (80) 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 81693937920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (167277035520).

81693937920 is an abundant number, since it is smaller than the sum of its proper divisors (252860133120).

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

81693937920 is a wasteful number, since it uses less digits than its factorization.

81693937920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 231 (or 217 counting only the distinct ones).

The product of its (nonzero) digits is 4408992, while the sum is 57.

The spelling of 81693937920 in words is "eighty-one billion, six hundred ninety-three million, nine hundred thirty-seven thousand, nine hundred twenty".