20568557 has 2 divisors, whose sum is σ = 20568558. Its totient is φ = 20568556.

The previous prime is 20568533. The next prime is 20568571. The reversal of 20568557 is 75586502.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 13498276 + 7070281 = 3674^2 + 2659^2 .

It is a cyclic number.

It is not a de Polignac number, because 20568557 - 2¹⁸ = 20306413 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 20568557.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20558557) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10284278 + 10284279.

It is an arithmetic number, because the mean of its divisors is an integer number (10284279).

Almost surely, 2^20568557 is an apocalyptic number.

It is an amenable number.

20568557 is a deficient number, since it is larger than the sum of its proper divisors (1).

20568557 is an equidigital number, since it uses as much as digits as its factorization.

20568557 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 84000, while the sum is 38.

The square root of 20568557 is about 4535.2571040681. The cubic root of 20568557 is about 273.9899342742.

The spelling of 20568557 in words is "twenty million, five hundred sixty-eight thousand, five hundred fifty-seven".