81364920 has 128 divisors (see below), whose sum is σ = 300464640. Its totient is φ = 17164800.

The previous prime is 81364919. The next prime is 81364939. The reversal of 81364920 is 2946318.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 7195 + ... + 14645.

It is an arithmetic number, because the mean of its divisors is an integer number (2347380).

Almost surely, 2^81364920 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 81364920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (150232320).

81364920 is an abundant number, since it is smaller than the sum of its proper divisors (219099720).

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

81364920 is a wasteful number, since it uses less digits than its factorization.

81364920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7485 (or 7481 counting only the distinct ones).

The product of its (nonzero) digits is 10368, while the sum is 33.

The square root of 81364920 is about 9020.2505508439. The cubic root of 81364920 is about 433.3236579036.

The spelling of 81364920 in words is "eighty-one million, three hundred sixty-four thousand, nine hundred twenty".