638682137 has 2 divisors, whose sum is σ = 638682138. Its totient is φ = 638682136.

The previous prime is 638682113. The next prime is 638682157. The reversal of 638682137 is 731286836.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 588499081 + 50183056 = 24259^2 + 7084^2 .

It is a cyclic number.

It is not a de Polignac number, because 638682137 - 2⁶ = 638682073 is a prime.

It is not a weakly prime, because it can be changed into another prime (638682157) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319341068 + 319341069.

It is an arithmetic number, because the mean of its divisors is an integer number (319341069).

Almost surely, 2^638682137 is an apocalyptic number.

It is an amenable number.

638682137 is a deficient number, since it is larger than the sum of its proper divisors (1).

638682137 is an equidigital number, since it uses as much as digits as its factorization.

638682137 is an evil number, because the sum of its binary digits is even.

The product of its digits is 290304, while the sum is 44.

The square root of 638682137 is about 25272.1613044868. The cubic root of 638682137 is about 861.1819591752.

The spelling of 638682137 in words is "six hundred thirty-eight million, six hundred eighty-two thousand, one hundred thirty-seven".