639723701 has 2 divisors, whose sum is σ = 639723702. Its totient is φ = 639723700.

The previous prime is 639723691. The next prime is 639723737. The reversal of 639723701 is 107327936.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 335256100 + 304467601 = 18310^2 + 17449^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-639723701 is a prime.

It is a super-2 number, since 2×639723701² = 818492827242274802, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (639723401) 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, 319861850 + 319861851.

It is an arithmetic number, because the mean of its divisors is an integer number (319861851).

Almost surely, 2^639723701 is an apocalyptic number.

It is an amenable number.

639723701 is a deficient number, since it is larger than the sum of its proper divisors (1).

639723701 is an equidigital number, since it uses as much as digits as its factorization.

639723701 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 47628, while the sum is 38.

The square root of 639723701 is about 25292.7598533652. The cubic root of 639723701 is about 861.6498439641.

The spelling of 639723701 in words is "six hundred thirty-nine million, seven hundred twenty-three thousand, seven hundred one".