638836128851 has 2 divisors, whose sum is σ = 638836128852. Its totient is φ = 638836128850.

The previous prime is 638836128817. The next prime is 638836128871. The reversal of 638836128851 is 158821638836.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-638836128851 is a prime.

It is a super-2 number, since 2×638836128851² (a number of 24 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (638836128871) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319418064425 + 319418064426.

It is an arithmetic number, because the mean of its divisors is an integer number (319418064426).

Almost surely, 2^638836128851 is an apocalyptic number.

638836128851 is a deficient number, since it is larger than the sum of its proper divisors (1).

638836128851 is an equidigital number, since it uses as much as digits as its factorization.

638836128851 is an evil number, because the sum of its binary digits is even.

The product of its digits is 13271040, while the sum is 59.

The spelling of 638836128851 in words is "six hundred thirty-eight billion, eight hundred thirty-six million, one hundred twenty-eight thousand, eight hundred fifty-one".