12856639 has 2 divisors, whose sum is σ = 12856640. Its totient is φ = 12856638.

The previous prime is 12856621. The next prime is 12856643. The reversal of 12856639 is 93665821.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 12856639 - 2¹⁵ = 12823871 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (12856339) 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, 6428319 + 6428320.

It is an arithmetic number, because the mean of its divisors is an integer number (6428320).

Almost surely, 2^12856639 is an apocalyptic number.

12856639 is a deficient number, since it is larger than the sum of its proper divisors (1).

12856639 is an equidigital number, since it uses as much as digits as its factorization.

12856639 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 77760, while the sum is 40.

The square root of 12856639 is about 3585.6155677931. The cubic root of 12856639 is about 234.2659393985.

The spelling of 12856639 in words is "twelve million, eight hundred fifty-six thousand, six hundred thirty-nine".