638702149 has 2 divisors, whose sum is σ = 638702150. Its totient is φ = 638702148.

The previous prime is 638702143. The next prime is 638702173. The reversal of 638702149 is 941207836.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 638320225 + 381924 = 25265^2 + 618^2 .

It is a cyclic number.

It is not a de Polignac number, because 638702149 - 2⁵ = 638702117 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (638702143) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319351074 + 319351075.

It is an arithmetic number, because the mean of its divisors is an integer number (319351075).

Almost surely, 2^638702149 is an apocalyptic number.

It is an amenable number.

638702149 is a deficient number, since it is larger than the sum of its proper divisors (1).

638702149 is an equidigital number, since it uses as much as digits as its factorization.

638702149 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 72576, while the sum is 40.

The square root of 638702149 is about 25272.5572311153. The cubic root of 638702149 is about 861.1909536302.

The spelling of 638702149 in words is "six hundred thirty-eight million, seven hundred two thousand, one hundred forty-nine".