79971921 has 8 divisors (see below), whose sum is σ = 118476960. Its totient is φ = 53314596.

The previous prime is 79971919. The next prime is 79971923. The reversal of 79971921 is 12917997.

It is an interprime number because it is at equal distance from previous prime (79971919) and next prime (79971923).

It is not a de Polignac number, because 79971921 - 2¹ = 79971919 is a prime.

It is not an unprimeable number, because it can be changed into a prime (79971923) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1480935 + ... + 1480988.

It is an arithmetic number, because the mean of its divisors is an integer number (14809620).

Almost surely, 2^79971921 is an apocalyptic number.

It is an amenable number.

79971921 is a deficient number, since it is larger than the sum of its proper divisors (38505039).

79971921 is a wasteful number, since it uses less digits than its factorization.

79971921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2961932 (or 2961926 counting only the distinct ones).

The product of its digits is 71442, while the sum is 45.

The square root of 79971921 is about 8942.7021084234. The cubic root of 79971921 is about 430.8365201309.

The spelling of 79971921 in words is "seventy-nine million, nine hundred seventy-one thousand, nine hundred twenty-one".