79721281 has 2 divisors, whose sum is σ = 79721282. Its totient is φ = 79721280.

The previous prime is 79721267. The next prime is 79721311. The reversal of 79721281 is 18212797.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 42706225 + 37015056 = 6535^2 + 6084^2 .

It is a cyclic number.

It is not a de Polignac number, because 79721281 - 2⁵ = 79721249 is a prime.

It is a super-2 number, since 2×79721281² = 12710965288561922, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 79721281.

It is not a weakly prime, because it can be changed into another prime (79721221) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39860640 + 39860641.

It is an arithmetic number, because the mean of its divisors is an integer number (39860641).

Almost surely, 2^79721281 is an apocalyptic number.

It is an amenable number.

79721281 is a deficient number, since it is larger than the sum of its proper divisors (1).

79721281 is an equidigital number, since it uses as much as digits as its factorization.

79721281 is an evil number, because the sum of its binary digits is even.

The product of its digits is 14112, while the sum is 37.

The square root of 79721281 is about 8928.6774496562. The cubic root of 79721281 is about 430.3859541794.

The spelling of 79721281 in words is "seventy-nine million, seven hundred twenty-one thousand, two hundred eighty-one".