639540701 has 2 divisors, whose sum is σ = 639540702. Its totient is φ = 639540700.

The previous prime is 639540689. The next prime is 639540751. The reversal of 639540701 is 107045936.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 638775076 + 765625 = 25274^2 + 875^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-639540701 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (639540751) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319770350 + 319770351.

It is an arithmetic number, because the mean of its divisors is an integer number (319770351).

Almost surely, 2^639540701 is an apocalyptic number.

It is an amenable number.

639540701 is a deficient number, since it is larger than the sum of its proper divisors (1).

639540701 is an equidigital number, since it uses as much as digits as its factorization.

639540701 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 22680, while the sum is 35.

The square root of 639540701 is about 25289.1419585560. The cubic root of 639540701 is about 861.5676746572.

The spelling of 639540701 in words is "six hundred thirty-nine million, five hundred forty thousand, seven hundred one".