79721881 has 2 divisors, whose sum is σ = 79721882. Its totient is φ = 79721880.

The previous prime is 79721843. The next prime is 79721903. The reversal of 79721881 is 18812797.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 47334400 + 32387481 = 6880^2 + 5691^2 .

It is an emirp because it is prime and its reverse (18812797) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 79721881 - 2¹¹ = 79719833 is a prime.

It is a super-2 number, since 2×79721881² = 12711156620356322, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (79721281) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39860940 + 39860941.

It is an arithmetic number, because the mean of its divisors is an integer number (39860941).

Almost surely, 2^79721881 is an apocalyptic number.

It is an amenable number.

79721881 is a deficient number, since it is larger than the sum of its proper divisors (1).

79721881 is an equidigital number, since it uses as much as digits as its factorization.

79721881 is an evil number, because the sum of its binary digits is even.

The product of its digits is 56448, while the sum is 43.

The square root of 79721881 is about 8928.7110491941. The cubic root of 79721881 is about 430.3870339033.

The spelling of 79721881 in words is "seventy-nine million, seven hundred twenty-one thousand, eight hundred eighty-one".