638989313 has 2 divisors, whose sum is σ = 638989314. Its totient is φ = 638989312.

The previous prime is 638989303. The next prime is 638989321. The reversal of 638989313 is 313989836.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 478384384 + 160604929 = 21872^2 + 12673^2 .

It is a cyclic number.

It is not a de Polignac number, because 638989313 - 2⁶ = 638989249 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (638989303) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319494656 + 319494657.

It is an arithmetic number, because the mean of its divisors is an integer number (319494657).

Almost surely, 2^638989313 is an apocalyptic number.

It is an amenable number.

638989313 is a deficient number, since it is larger than the sum of its proper divisors (1).

638989313 is an equidigital number, since it uses as much as digits as its factorization.

638989313 is an evil number, because the sum of its binary digits is even.

The product of its digits is 839808, while the sum is 50.

The square root of 638989313 is about 25278.2379330522. The cubic root of 638989313 is about 861.3199996891.

The spelling of 638989313 in words is "six hundred thirty-eight million, nine hundred eighty-nine thousand, three hundred thirteen".