638669136 has 240 divisors, whose sum is σ = 2030495040. Its totient is φ = 172247040.

The previous prime is 638669131. The next prime is 638669167. The reversal of 638669136 is 631966836.

It is a Harshad number since it is a multiple of its sum of digits (48).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (638669131) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 3567895 + ... + 3568073.

It is an arithmetic number, because the mean of its divisors is an integer number (8460396).

Almost surely, 2^638669136 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 638669136, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1015247520).

638669136 is an abundant number, since it is smaller than the sum of its proper divisors (1391825904).

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

638669136 is a wasteful number, since it uses less digits than its factorization.

638669136 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 282 (or 269 counting only the distinct ones).

The product of its digits is 839808, while the sum is 48.

The square root of 638669136 is about 25271.9040833887. The cubic root of 638669136 is about 861.1761157350.

The spelling of 638669136 in words is "six hundred thirty-eight million, six hundred sixty-nine thousand, one hundred thirty-six".