79129921 has 8 divisors (see below), whose sum is σ = 85310120. Its totient is φ = 72963072.

The previous prime is 79129909. The next prime is 79129931. The reversal of 79129921 is 12992197.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 9641025 + 69488896 = 3105^2 + 8336^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a de Polignac number, because none of the positive numbers 2^k-79129921 is a prime.

It is the 8896-th Hogben number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (79129931) by changing a digit.

It is a nontrivial repunit in base 8895.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 11425 + ... + 16993.

It is an arithmetic number, because the mean of its divisors is an integer number (10663765).

Almost surely, 2^79129921 is an apocalyptic number.

It is an amenable number.

79129921 is a deficient number, since it is larger than the sum of its proper divisors (6180199).

79129921 is a wasteful number, since it uses less digits than its factorization.

79129921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6675.

The product of its digits is 20412, while the sum is 40.

The square root of 79129921 is about 8895.5000421561. The cubic root of 79129921 is about 429.3191334024.

The spelling of 79129921 in words is "seventy-nine million, one hundred twenty-nine thousand, nine hundred twenty-one".