81379968 has 32 divisors (see below), whose sum is σ = 216166560. Its totient is φ = 27126528.

The previous prime is 81379937. The next prime is 81379979. The reversal of 81379968 is 86997318.

It is a tau number, because it is divible by the number of its divisors (32).

It is a self number, because there is not a number n which added to its sum of digits gives 81379968.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 105580 + ... + 106347.

It is an arithmetic number, because the mean of its divisors is an integer number (6755205).

Almost surely, 2^81379968 is an apocalyptic number.

It is an amenable number.

81379968 is an abundant number, since it is smaller than the sum of its proper divisors (134786592).

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

81379968 is a wasteful number, since it uses less digits than its factorization.

81379968 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 211944 (or 211932 counting only the distinct ones).

The product of its digits is 653184, while the sum is 51.

The square root of 81379968 is about 9021.0846354527. The cubic root of 81379968 is about 433.3503698759.

The spelling of 81379968 in words is "eighty-one million, three hundred seventy-nine thousand, nine hundred sixty-eight".