79961621 has 2 divisors, whose sum is σ = 79961622. Its totient is φ = 79961620.

The previous prime is 79961573. The next prime is 79961653. The reversal of 79961621 is 12616997.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 79299025 + 662596 = 8905^2 + 814^2 .

It is an emirp because it is prime and its reverse (12616997) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-79961621 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (79961821) 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 as a sum of consecutive naturals, namely, 39980810 + 39980811.

It is an arithmetic number, because the mean of its divisors is an integer number (39980811).

Almost surely, 2^79961621 is an apocalyptic number.

It is an amenable number.

79961621 is a deficient number, since it is larger than the sum of its proper divisors (1).

79961621 is an equidigital number, since it uses as much as digits as its factorization.

79961621 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 40824, while the sum is 41.

The square root of 79961621 is about 8942.1262013013. The cubic root of 79961621 is about 430.8180227773.

The spelling of 79961621 in words is "seventy-nine million, nine hundred sixty-one thousand, six hundred twenty-one".