81713920 has 36 divisors (see below), whose sum is σ = 195733440. Its totient is φ = 32685056.

The previous prime is 81713899. The next prime is 81713939. The reversal of 81713920 is 2931718.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 30640 + ... + 33199.

It is an arithmetic number, because the mean of its divisors is an integer number (5437040).

Almost surely, 2^81713920 is an apocalyptic number.

81713920 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

81713920 is an abundant number, since it is smaller than the sum of its proper divisors (114019520).

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

81713920 is an equidigital number, since it uses as much as digits as its factorization.

81713920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 63860 (or 63846 counting only the distinct ones).

The product of its (nonzero) digits is 3024, while the sum is 31.

The square root of 81713920 is about 9039.5752112585. The cubic root of 81713920 is about 433.9423284803.

The spelling of 81713920 in words is "eighty-one million, seven hundred thirteen thousand, nine hundred twenty".