79311981 has 32 divisors (see below), whose sum is σ = 130203648. Its totient is φ = 41944320.

The previous prime is 79311977. The next prime is 79312001. The reversal of 79311981 is 18911397.

It is not a de Polignac number, because 79311981 - 2² = 79311977 is a prime.

It is a super-2 number, since 2×79311981² = 12580780660288722, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (79311901) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 12325 + ... + 17621.

It is an arithmetic number, because the mean of its divisors is an integer number (4068864).

Almost surely, 2^79311981 is an apocalyptic number.

It is an amenable number.

79311981 is a deficient number, since it is larger than the sum of its proper divisors (50891667).

79311981 is a wasteful number, since it uses less digits than its factorization.

79311981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5361.

The product of its digits is 13608, while the sum is 39.

The square root of 79311981 is about 8905.7274267743. The cubic root of 79311981 is about 429.6481365267.

The spelling of 79311981 in words is "seventy-nine million, three hundred eleven thousand, nine hundred eighty-one".