638109313 has 2 divisors, whose sum is σ = 638109314. Its totient is φ = 638109312.

The previous prime is 638109259. The next prime is 638109323. The reversal of 638109313 is 313901836.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 503015184 + 135094129 = 22428^2 + 11623^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-638109313 is a prime.

It is not a weakly prime, because it can be changed into another prime (638109323) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319054656 + 319054657.

It is an arithmetic number, because the mean of its divisors is an integer number (319054657).

Almost surely, 2^638109313 is an apocalyptic number.

It is an amenable number.

638109313 is a deficient number, since it is larger than the sum of its proper divisors (1).

638109313 is an equidigital number, since it uses as much as digits as its factorization.

638109313 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 11664, while the sum is 34.

The square root of 638109313 is about 25260.8256595069. The cubic root of 638109313 is about 860.9244219649.

The spelling of 638109313 in words is "six hundred thirty-eight million, one hundred nine thousand, three hundred thirteen".