638803021 has 2 divisors, whose sum is σ = 638803022. Its totient is φ = 638803020.

The previous prime is 638803007. The next prime is 638803027. The reversal of 638803021 is 120308836.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 515925796 + 122877225 = 22714^2 + 11085^2 .

It is a cyclic number.

It is not a de Polignac number, because 638803021 - 2¹⁷ = 638671949 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (638803027) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319401510 + 319401511.

It is an arithmetic number, because the mean of its divisors is an integer number (319401511).

Almost surely, 2^638803021 is an apocalyptic number.

It is an amenable number.

638803021 is a deficient number, since it is larger than the sum of its proper divisors (1).

638803021 is an equidigital number, since it uses as much as digits as its factorization.

638803021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 6912, while the sum is 31.

The square root of 638803021 is about 25274.5528348179. The cubic root of 638803021 is about 861.2362880015.

The spelling of 638803021 in words is "six hundred thirty-eight million, eight hundred three thousand, twenty-one".