72979821 has 6 divisors (see below), whose sum is σ = 105415310. Its totient is φ = 48653208.

The previous prime is 72979813. The next prime is 72979843. The reversal of 72979821 is 12897927.

It can be written as a sum of positive squares in only one way, i.e., 42575625 + 30404196 = 6525^2 + 5514^2 .

It is not a de Polignac number, because 72979821 - 2³ = 72979813 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 (72979871) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 4054426 + ... + 4054443.

Almost surely, 2^72979821 is an apocalyptic number.

It is an amenable number.

72979821 is a deficient number, since it is larger than the sum of its proper divisors (32435489).

72979821 is a wasteful number, since it uses less digits than its factorization.

72979821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8108875 (or 8108872 counting only the distinct ones).

The product of its digits is 127008, while the sum is 45.

The square root of 72979821 is about 8542.8227770451. The cubic root of 72979821 is about 417.8954070091.

The spelling of 72979821 in words is "seventy-two million, nine hundred seventy-nine thousand, eight hundred twenty-one".