639943201 has 2 divisors, whose sum is σ = 639943202. Its totient is φ = 639943200.

The previous prime is 639943169. The next prime is 639943219. The reversal of 639943201 is 102349936.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 623750625 + 16192576 = 24975^2 + 4024^2 .

It is a cyclic number.

It is not a de Polignac number, because 639943201 - 2⁵ = 639943169 is a prime.

It is a super-2 number, since 2×639943201² = 819054601012252802, which contains 22 as substring.

It is a pancake number, because a pancake can be divided into 639943201 parts by 35775 straight cuts.

It is equal to p_33297652 and since 639943201 and 33297652 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (639943901) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319971600 + 319971601.

It is an arithmetic number, because the mean of its divisors is an integer number (319971601).

Almost surely, 2^639943201 is an apocalyptic number.

It is an amenable number.

639943201 is a deficient number, since it is larger than the sum of its proper divisors (1).

639943201 is an equidigital number, since it uses as much as digits as its factorization.

639943201 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 34992, while the sum is 37.

The square root of 639943201 is about 25297.0986676338. The cubic root of 639943201 is about 861.7483815635.

The spelling of 639943201 in words is "six hundred thirty-nine million, nine hundred forty-three thousand, two hundred one".