79721644 has 24 divisors (see below), whose sum is σ = 147188160. Its totient is φ = 37677456.

The previous prime is 79721641. The next prime is 79721651. The reversal of 79721644 is 44612797.

It is a junction number, because it is equal to n+sod(n) for n = 79721597 and 79721606.

It is not an unprimeable number, because it can be changed into a prime (79721641) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 43719 + ... + 45505.

It is an arithmetic number, because the mean of its divisors is an integer number (6132840).

Almost surely, 2^79721644 is an apocalyptic number.

It is an amenable number.

79721644 is a deficient number, since it is larger than the sum of its proper divisors (67466516).

79721644 is a wasteful number, since it uses less digits than its factorization.

79721644 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2397 (or 2395 counting only the distinct ones).

The product of its digits is 84672, while the sum is 40.

The square root of 79721644 is about 8928.6977773917. The cubic root of 79721644 is about 430.3866074130.

The spelling of 79721644 in words is "seventy-nine million, seven hundred twenty-one thousand, six hundred forty-four".