79639561 has 2 divisors, whose sum is σ = 79639562. Its totient is φ = 79639560.

The previous prime is 79639537. The next prime is 79639591. The reversal of 79639561 is 16593697.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 69622336 + 10017225 = 8344^2 + 3165^2 .

It is an emirp because it is prime and its reverse (16593697) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 79639561 - 2⁵ = 79639529 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (79639591) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39819780 + 39819781.

It is an arithmetic number, because the mean of its divisors is an integer number (39819781).

Almost surely, 2^79639561 is an apocalyptic number.

It is an amenable number.

79639561 is a deficient number, since it is larger than the sum of its proper divisors (1).

79639561 is an equidigital number, since it uses as much as digits as its factorization.

79639561 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 306180, while the sum is 46.

The square root of 79639561 is about 8924.1000106453. The cubic root of 79639561 is about 430.2388451339.

It can be divided in two parts, 79639 and 561, that added together give a triangular number (80200 = T₄₀₀).

The spelling of 79639561 in words is "seventy-nine million, six hundred thirty-nine thousand, five hundred sixty-one".