639722603521 has 2 divisors, whose sum is σ = 639722603522. Its totient is φ = 639722603520.

The previous prime is 639722603519. The next prime is 639722603551. The reversal of 639722603521 is 125306227936.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 581947751025 + 57774852496 = 762855^2 + 240364^2 .

It is a cyclic number.

It is not a de Polignac number, because 639722603521 - 2¹ = 639722603519 is a prime.

Together with 639722603519, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (639722603551) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319861301760 + 319861301761.

It is an arithmetic number, because the mean of its divisors is an integer number (319861301761).

Almost surely, 2^639722603521 is an apocalyptic number.

It is an amenable number.

639722603521 is a deficient number, since it is larger than the sum of its proper divisors (1).

639722603521 is an equidigital number, since it uses as much as digits as its factorization.

639722603521 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 816480, while the sum is 46.

The spelling of 639722603521 in words is "six hundred thirty-nine billion, seven hundred twenty-two million, six hundred three thousand, five hundred twenty-one".