79929821 has 4 divisors (see below), whose sum is σ = 80420352. Its totient is φ = 79439292.

The previous prime is 79929803. The next prime is 79929823. The reversal of 79929821 is 12892997.

It is a happy number.

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 a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-79929821 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (79929823) 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, 245021 + ... + 245346.

It is an arithmetic number, because the mean of its divisors is an integer number (20105088).

Almost surely, 2^79929821 is an apocalyptic number.

It is an amenable number.

79929821 is a deficient number, since it is larger than the sum of its proper divisors (490531).

79929821 is a wasteful number, since it uses less digits than its factorization.

79929821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 490530.

The product of its digits is 163296, while the sum is 47.

The square root of 79929821 is about 8940.3479238786. The cubic root of 79929821 is about 430.7609044186.

The spelling of 79929821 in words is "seventy-nine million, nine hundred twenty-nine thousand, eight hundred twenty-one".