81200920 has 32 divisors (see below), whose sum is σ = 183283920. Its totient is φ = 32376960.

The previous prime is 81200849. The next prime is 81200939. The reversal of 81200920 is 2900218.

It is a junction number, because it is equal to n+sod(n) for n = 81200891 and 81200900.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 10174 + ... + 16306.

Almost surely, 2^81200920 is an apocalyptic number.

It is an amenable number.

81200920 is an abundant number, since it is smaller than the sum of its proper divisors (102083000).

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

81200920 is a wasteful number, since it uses less digits than its factorization.

81200920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6475 (or 6471 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 22.

The square root of 81200920 is about 9011.1553088380. The cubic root of 81200920 is about 433.0323248167.

The spelling of 81200920 in words is "eighty-one million, two hundred thousand, nine hundred twenty".