639974771 has 2 divisors, whose sum is σ = 639974772. Its totient is φ = 639974770.

The previous prime is 639974749. The next prime is 639974789. The reversal of 639974771 is 177479936.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-639974771 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (639074771) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319987385 + 319987386.

It is an arithmetic number, because the mean of its divisors is an integer number (319987386).

Almost surely, 2^639974771 is an apocalyptic number.

639974771 is a deficient number, since it is larger than the sum of its proper divisors (1).

639974771 is an equidigital number, since it uses as much as digits as its factorization.

639974771 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2000376, while the sum is 53.

The square root of 639974771 is about 25297.7226445386. The cubic root of 639974771 is about 861.7625520655.

The spelling of 639974771 in words is "six hundred thirty-nine million, nine hundred seventy-four thousand, seven hundred seventy-one".