79919821 has 8 divisors (see below), whose sum is σ = 81505944. Its totient is φ = 78342720.

The previous prime is 79919809. The next prime is 79919831. The reversal of 79919821 is 12891997.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 264196 + 79655625 = 514^2 + 8925^2 .

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-79919821 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 (79919831) 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, 17271 + ... + 21403.

It is an arithmetic number, because the mean of its divisors is an integer number (10188243).

Almost surely, 2^79919821 is an apocalyptic number.

It is an amenable number.

79919821 is a deficient number, since it is larger than the sum of its proper divisors (1586123).

79919821 is a wasteful number, since it uses less digits than its factorization.

79919821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4511.

The product of its digits is 81648, while the sum is 46.

The square root of 79919821 is about 8939.7886440340. The cubic root of 79919821 is about 430.7429395396.

The spelling of 79919821 in words is "seventy-nine million, nine hundred nineteen thousand, eight hundred twenty-one".