20499990557 has 2 divisors, whose sum is σ = 20499990558. Its totient is φ = 20499990556.

The previous prime is 20499990499. The next prime is 20499990593. The reversal of 20499990557 is 75509999402.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 14645598361 + 5854392196 = 121019^2 + 76514^2 .

It is a cyclic number.

It is not a de Polignac number, because 20499990557 - 2²⁴ = 20483213341 is a prime.

It is a super-2 number, since 2×20499990557² (a number of 21 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 20499990496 and 20499990505.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20499990157) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10249995278 + 10249995279.

It is an arithmetic number, because the mean of its divisors is an integer number (10249995279).

Almost surely, 2^20499990557 is an apocalyptic number.

It is an amenable number.

20499990557 is a deficient number, since it is larger than the sum of its proper divisors (1).

20499990557 is an equidigital number, since it uses as much as digits as its factorization.

20499990557 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 9185400, while the sum is 59.

The spelling of 20499990557 in words is "twenty billion, four hundred ninety-nine million, nine hundred ninety thousand, five hundred fifty-seven".