79971591 has 16 divisors (see below), whose sum is σ = 122415104. Its totient is φ = 45490464.

The previous prime is 79971557. The next prime is 79971601. The reversal of 79971591 is 19517997.

It is a happy number.

It is not a de Polignac number, because 79971591 - 2⁶ = 79971527 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 79971591.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (79971691) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3856 + ... + 13221.

It is an arithmetic number, because the mean of its divisors is an integer number (7650944).

Almost surely, 2^79971591 is an apocalyptic number.

79971591 is a deficient number, since it is larger than the sum of its proper divisors (42443513).

79971591 is a wasteful number, since it uses less digits than its factorization.

79971591 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17310.

The product of its digits is 178605, while the sum is 48.

The square root of 79971591 is about 8942.6836576052. The cubic root of 79971591 is about 430.8359275218.

It can be divided in two parts, 799 and 71591, that added together give a triangular number (72390 = T₃₈₀).

The spelling of 79971591 in words is "seventy-nine million, nine hundred seventy-one thousand, five hundred ninety-one".