20638756257 has 16 divisors (see below), whose sum is σ = 31607577600. Its totient is φ = 11734308432.

The previous prime is 20638756247. The next prime is 20638756283. The reversal of 20638756257 is 75265783602.

It is a happy number.

It is not a de Polignac number, because 20638756257 - 2¹⁵ = 20638723489 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20638756247) 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 in 15 ways as a sum of consecutive naturals, for example, 2465163 + ... + 2473520.

It is an arithmetic number, because the mean of its divisors is an integer number (1975473600).

Almost surely, 2^20638756257 is an apocalyptic number.

It is an amenable number.

20638756257 is a deficient number, since it is larger than the sum of its proper divisors (10968821343).

20638756257 is a wasteful number, since it uses less digits than its factorization.

20638756257 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4938892.

The product of its (nonzero) digits is 4233600, while the sum is 51.

The spelling of 20638756257 in words is "twenty billion, six hundred thirty-eight million, seven hundred fifty-six thousand, two hundred fifty-seven".