20502791857 has 2 divisors, whose sum is σ = 20502791858. Its totient is φ = 20502791856.

The previous prime is 20502791849. The next prime is 20502791891. The reversal of 20502791857 is 75819720502.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20392982416 + 109809441 = 142804^2 + 10479^2 .

It is a cyclic number.

It is not a de Polignac number, because 20502791857 - 2³ = 20502791849 is a prime.

It is not a weakly prime, because it can be changed into another prime (20502791657) 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, 10251395928 + 10251395929.

It is an arithmetic number, because the mean of its divisors is an integer number (10251395929).

Almost surely, 2^20502791857 is an apocalyptic number.

It is an amenable number.

20502791857 is a deficient number, since it is larger than the sum of its proper divisors (1).

20502791857 is an equidigital number, since it uses as much as digits as its factorization.

20502791857 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 352800, while the sum is 46.

The spelling of 20502791857 in words is "twenty billion, five hundred two million, seven hundred ninety-one thousand, eight hundred fifty-seven".