639573361421 has 2 divisors, whose sum is σ = 639573361422. Its totient is φ = 639573361420.

The previous prime is 639573361411. The next prime is 639573361457. The reversal of 639573361421 is 124163375936.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 409010132521 + 230563228900 = 639539^2 + 480170^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-639573361421 is a prime.

It is a super-2 number, since 2×639573361421² (a number of 24 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 639573361421.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (639573361411) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319786680710 + 319786680711.

It is an arithmetic number, because the mean of its divisors is an integer number (319786680711).

Almost surely, 2^639573361421 is an apocalyptic number.

It is an amenable number.

639573361421 is a deficient number, since it is larger than the sum of its proper divisors (1).

639573361421 is an equidigital number, since it uses as much as digits as its factorization.

639573361421 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2449440, while the sum is 50.

The spelling of 639573361421 in words is "six hundred thirty-nine billion, five hundred seventy-three million, three hundred sixty-one thousand, four hundred twenty-one".