15639979 has 2 divisors, whose sum is σ = 15639980. Its totient is φ = 15639978.

The previous prime is 15639947. The next prime is 15639997. The reversal of 15639979 is 97993651.

Together with next prime (15639997) it forms an Ormiston pair, because they use the same digits, order apart.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 15639979 - 2⁵ = 15639947 is a prime.

It is not a weakly prime, because it can be changed into another prime (15639079) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 7819989 + 7819990.

It is an arithmetic number, because the mean of its divisors is an integer number (7819990).

Almost surely, 2^15639979 is an apocalyptic number.

15639979 is a deficient number, since it is larger than the sum of its proper divisors (1).

15639979 is an equidigital number, since it uses as much as digits as its factorization.

15639979 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 459270, while the sum is 49.

The square root of 15639979 is about 3954.7413316170. The cubic root of 15639979 is about 250.0798624852.

The spelling of 15639979 in words is "fifteen million, six hundred thirty-nine thousand, nine hundred seventy-nine".