20490557 has 2 divisors, whose sum is σ = 20490558. Its totient is φ = 20490556.

The previous prime is 20490551. The next prime is 20490599. The reversal of 20490557 is 75509402.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13205956 + 7284601 = 3634^2 + 2699^2 .

It is a cyclic number.

It is not a de Polignac number, because 20490557 - 2¹⁶ = 20425021 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20490551) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10245278 + 10245279.

It is an arithmetic number, because the mean of its divisors is an integer number (10245279).

Almost surely, 2^20490557 is an apocalyptic number.

It is an amenable number.

20490557 is a deficient number, since it is larger than the sum of its proper divisors (1).

20490557 is an equidigital number, since it uses as much as digits as its factorization.

20490557 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 12600, while the sum is 32.

The square root of 20490557 is about 4526.6496440524. The cubic root of 20490557 is about 273.6431543722.

Adding to 20490557 its reverse (75509402), we get a palindrome (95999959).

The spelling of 20490557 in words is "twenty million, four hundred ninety thousand, five hundred fifty-seven".