639822401 has 2 divisors, whose sum is σ = 639822402. Its totient is φ = 639822400.

The previous prime is 639822383. The next prime is 639822437. The reversal of 639822401 is 104228936.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 637512001 + 2310400 = 25249^2 + 1520^2 .

It is a cyclic number.

It is not a de Polignac number, because 639822401 - 2¹⁴ = 639806017 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (639822451) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319911200 + 319911201.

It is an arithmetic number, because the mean of its divisors is an integer number (319911201).

Almost surely, 2^639822401 is an apocalyptic number.

It is an amenable number.

639822401 is a deficient number, since it is larger than the sum of its proper divisors (1).

639822401 is an equidigital number, since it uses as much as digits as its factorization.

639822401 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 20736, while the sum is 35.

The square root of 639822401 is about 25294.7109293623. The cubic root of 639822401 is about 861.6941550035.

The spelling of 639822401 in words is "six hundred thirty-nine million, eight hundred twenty-two thousand, four hundred one".