20856679 has 2 divisors, whose sum is σ = 20856680. Its totient is φ = 20856678.

The previous prime is 20856629. The next prime is 20856709. The reversal of 20856679 is 97665802.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 20856679 - 2⁷ = 20856551 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20856629) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10428339 + 10428340.

It is an arithmetic number, because the mean of its divisors is an integer number (10428340).

Almost surely, 2^20856679 is an apocalyptic number.

20856679 is a deficient number, since it is larger than the sum of its proper divisors (1).

20856679 is an equidigital number, since it uses as much as digits as its factorization.

20856679 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 181440, while the sum is 43.

The square root of 20856679 is about 4566.9113194806. The cubic root of 20856679 is about 275.2633466305.

The spelling of 20856679 in words is "twenty million, eight hundred fifty-six thousand, six hundred seventy-nine".