79521681 has 4 divisors (see below), whose sum is σ = 106028912. Its totient is φ = 53014452.

The previous prime is 79521679. The next prime is 79521709. The reversal of 79521681 is 18612597.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 79521681 - 2¹ = 79521679 is a prime.

It is a super-2 number, since 2×79521681² = 12647395498131522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (79521641) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 13253611 + ... + 13253616.

It is an arithmetic number, because the mean of its divisors is an integer number (26507228).

Almost surely, 2^79521681 is an apocalyptic number.

It is an amenable number.

79521681 is a deficient number, since it is larger than the sum of its proper divisors (26507231).

79521681 is a wasteful number, since it uses less digits than its factorization.

79521681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26507230.

The product of its digits is 30240, while the sum is 39.

The square root of 79521681 is about 8917.4929772891. The cubic root of 79521681 is about 430.0264649296.

The spelling of 79521681 in words is "seventy-nine million, five hundred twenty-one thousand, six hundred eighty-one".