20564839 has 2 divisors, whose sum is σ = 20564840. Its totient is φ = 20564838.

The previous prime is 20564833. The next prime is 20564867. The reversal of 20564839 is 93846502.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20564839 - 2⁵ = 20564807 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 20564798 and 20564807.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20564833) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10282419 + 10282420.

It is an arithmetic number, because the mean of its divisors is an integer number (10282420).

Almost surely, 2^20564839 is an apocalyptic number.

20564839 is a deficient number, since it is larger than the sum of its proper divisors (1).

20564839 is an equidigital number, since it uses as much as digits as its factorization.

20564839 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 51840, while the sum is 37.

The square root of 20564839 is about 4534.8471859590. The cubic root of 20564839 is about 273.9734243499.

The spelling of 20564839 in words is "twenty million, five hundred sixty-four thousand, eight hundred thirty-nine".