638263764 has 72 divisors (see below), whose sum is σ = 1662952200. Its totient is φ = 206260992.

The previous prime is 638263763. The next prime is 638263771. The reversal of 638263764 is 467362836.

638263764 is a `hidden beast` number, since 6 + 3 + 8 + 2 + 637 + 6 + 4 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 496844100 + 141419664 = 22290^2 + 11892^2 .

It is a hoax number, since the sum of its digits (45) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (638263763) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 464182 + ... + 465554.

Almost surely, 2^638263764 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 638263764, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (831476100).

638263764 is an abundant number, since it is smaller than the sum of its proper divisors (1024688436).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

638263764 is a wasteful number, since it uses less digits than its factorization.

638263764 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1769 (or 1764 counting only the distinct ones).

The product of its digits is 870912, while the sum is 45.

The square root of 638263764 is about 25263.8825994739. The cubic root of 638263764 is about 860.9938771028.

The spelling of 638263764 in words is "six hundred thirty-eight million, two hundred sixty-three thousand, seven hundred sixty-four".