81924769920 has 768 divisors, whose sum is σ = 316819278720. Its totient is φ = 17939496960.

The previous prime is 81924769873. The next prime is 81924769931. The reversal of 81924769920 is 2996742918.

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 258437602 + ... + 258437918.

Almost surely, 2^81924769920 is an apocalyptic number.

81924769920 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 81924769920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (158409639360).

81924769920 is an abundant number, since it is smaller than the sum of its proper divisors (234894508800).

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

81924769920 is a wasteful number, since it uses less digits than its factorization.

81924769920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 461 (or 442 counting only the distinct ones).

The product of its (nonzero) digits is 3919104, while the sum is 57.

The spelling of 81924769920 in words is "eighty-one billion, nine hundred twenty-four million, seven hundred sixty-nine thousand, nine hundred twenty".