638531265 has 16 divisors (see below), whose sum is σ = 1031025600. Its totient is φ = 337424832.

The previous prime is 638531263. The next prime is 638531269. The reversal of 638531265 is 562135836.

It is not a de Polignac number, because 638531265 - 2¹ = 638531263 is a prime.

It is not an unprimeable number, because it can be changed into a prime (638531263) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 193635 + ... + 196904.

It is an arithmetic number, because the mean of its divisors is an integer number (64439100).

Almost surely, 2^638531265 is an apocalyptic number.

It is an amenable number.

638531265 is a deficient number, since it is larger than the sum of its proper divisors (392494335).

638531265 is a wasteful number, since it uses less digits than its factorization.

638531265 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 390656.

The product of its digits is 129600, while the sum is 39.

The square root of 638531265 is about 25269.1761836432. The cubic root of 638531265 is about 861.1141432413.

The spelling of 638531265 in words is "six hundred thirty-eight million, five hundred thirty-one thousand, two hundred sixty-five".