639643445933 has 2 divisors, whose sum is σ = 639643445934. Its totient is φ = 639643445932.

The previous prime is 639643445879. The next prime is 639643445963. The reversal of 639643445933 is 339544346936.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 399427792009 + 240215653924 = 632003^2 + 490118^2 .

It is a cyclic number.

It is not a de Polignac number, because 639643445933 - 2⁸ = 639643445677 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (639643445963) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319821722966 + 319821722967.

It is an arithmetic number, because the mean of its divisors is an integer number (319821722967).

Almost surely, 2^639643445933 is an apocalyptic number.

It is an amenable number.

639643445933 is a deficient number, since it is larger than the sum of its proper divisors (1).

639643445933 is an equidigital number, since it uses as much as digits as its factorization.

639643445933 is an evil number, because the sum of its binary digits is even.

The product of its digits is 75582720, while the sum is 59.

The spelling of 639643445933 in words is "six hundred thirty-nine billion, six hundred forty-three million, four hundred forty-five thousand, nine hundred thirty-three".