638139265 has 4 divisors (see below), whose sum is σ = 765767124. Its totient is φ = 510511408.

The previous prime is 638139223. The next prime is 638139317. The reversal of 638139265 is 562931836.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 249103089 + 389036176 = 15783^2 + 19724^2 .

It is a cyclic number.

It is not a de Polignac number, because 638139265 - 2¹³ = 638131073 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 63813922 + ... + 63813931.

It is an arithmetic number, because the mean of its divisors is an integer number (191441781).

Almost surely, 2^638139265 is an apocalyptic number.

It is an amenable number.

638139265 is a deficient number, since it is larger than the sum of its proper divisors (127627859).

638139265 is a wasteful number, since it uses less digits than its factorization.

638139265 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 127627858.

The product of its digits is 233280, while the sum is 43.

The square root of 638139265 is about 25261.4185072810. The cubic root of 638139265 is about 860.9378919688.

The spelling of 638139265 in words is "six hundred thirty-eight million, one hundred thirty-nine thousand, two hundred sixty-five".