81984720 has 40 divisors (see below), whose sum is σ = 254153376. Its totient is φ = 21862528.

The previous prime is 81984713. The next prime is 81984733. The reversal of 81984720 is 2748918.

It is a tau number, because it is divible by the number of its divisors (40).

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, 170562 + ... + 171041.

Almost surely, 2^81984720 is an apocalyptic number.

81984720 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

81984720 is an abundant number, since it is smaller than the sum of its proper divisors (172168656).

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

81984720 is a wasteful number, since it uses less digits than its factorization.

81984720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 341619 (or 341613 counting only the distinct ones).

The product of its (nonzero) digits is 32256, while the sum is 39.

The square root of 81984720 is about 9054.5414019706. The cubic root of 81984720 is about 434.4211616659.

The spelling of 81984720 in words is "eighty-one million, nine hundred eighty-four thousand, seven hundred twenty".