20513173957 has 2 divisors, whose sum is σ = 20513173958. Its totient is φ = 20513173956.

The previous prime is 20513173931. The next prime is 20513173973. The reversal of 20513173957 is 75937131502.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16960894756 + 3552279201 = 130234^2 + 59601^2 .

It is a cyclic number.

It is not a de Polignac number, because 20513173957 - 2¹⁵ = 20513141189 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20513173157) 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, 10256586978 + 10256586979.

It is an arithmetic number, because the mean of its divisors is an integer number (10256586979).

Almost surely, 2^20513173957 is an apocalyptic number.

It is an amenable number.

20513173957 is a deficient number, since it is larger than the sum of its proper divisors (1).

20513173957 is an equidigital number, since it uses as much as digits as its factorization.

20513173957 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 198450, while the sum is 43.

The spelling of 20513173957 in words is "twenty billion, five hundred thirteen million, one hundred seventy-three thousand, nine hundred fifty-seven".