639540751 has 2 divisors, whose sum is σ = 639540752. Its totient is φ = 639540750.

The previous prime is 639540701. The next prime is 639540773. The reversal of 639540751 is 157045936.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 639540751 - 2²⁵ = 605986319 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (639540701) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319770375 + 319770376.

It is an arithmetic number, because the mean of its divisors is an integer number (319770376).

Almost surely, 2^639540751 is an apocalyptic number.

639540751 is a deficient number, since it is larger than the sum of its proper divisors (1).

639540751 is an equidigital number, since it uses as much as digits as its factorization.

639540751 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 113400, while the sum is 40.

The square root of 639540751 is about 25289.1429471226. The cubic root of 639540751 is about 861.5676971100.

The spelling of 639540751 in words is "six hundred thirty-nine million, five hundred forty thousand, seven hundred fifty-one".