81992900 has 72 divisors (see below), whose sum is σ = 195924960. Its totient is φ = 29536000.

The previous prime is 81992899. The next prime is 81992909. The reversal of 81992900 is 929918.

It is not an unprimeable number, because it can be changed into a prime (81992909) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 143816 + ... + 144384.

It is an arithmetic number, because the mean of its divisors is an integer number (2721180).

Almost surely, 2^81992900 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81992900, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (97962480).

81992900 is an abundant number, since it is smaller than the sum of its proper divisors (113932060).

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

81992900 is a wasteful number, since it uses less digits than its factorization.

81992900 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 725 (or 718 counting only the distinct ones).

The product of its (nonzero) digits is 11664, while the sum is 38.

The square root of 81992900 is about 9054.9930977334. The cubic root of 81992900 is about 434.4356092643.

The spelling of 81992900 in words is "eighty-one million, nine hundred ninety-two thousand, nine hundred".