638323920 has 240 divisors, whose sum is σ = 2359348992. Its totient is φ = 153676800.

The previous prime is 638323919. The next prime is 638323937. The reversal of 638323920 is 29323836.

It is a tau number, because it is divible by the number of its divisors (240).

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 439195 + ... + 440645.

Almost surely, 2^638323920 is an apocalyptic number.

638323920 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 638323920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1179674496).

638323920 is an abundant number, since it is smaller than the sum of its proper divisors (1721025072).

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

638323920 is a wasteful number, since it uses less digits than its factorization.

638323920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1530 (or 1521 counting only the distinct ones).

The product of its (nonzero) digits is 46656, while the sum is 36.

The square root of 638323920 is about 25265.0731247705. The cubic root of 638323920 is about 861.0209256489.

It can be divided in two parts, 6383 and 23920, that added together give a palindrome (30303).

The spelling of 638323920 in words is "six hundred thirty-eight million, three hundred twenty-three thousand, nine hundred twenty".