638426880 has 864 divisors, whose sum is σ = 2936001600. Its totient is φ = 130056192.

The previous prime is 638426863. The next prime is 638426881. The reversal of 638426880 is 88624836.

It is a happy number.

638426880 is a `hidden beast` number, since 6 + 384 + 268 + 8 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (864).

It is a super-2 number, since 2×638426880² = 815177762213068800, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (638426881) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 22014706 + ... + 22014734.

It is an arithmetic number, because the mean of its divisors is an integer number (3398150).

Almost surely, 2^638426880 is an apocalyptic number.

638426880 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 638426880, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1468000800).

638426880 is an abundant number, since it is smaller than the sum of its proper divisors (2297574720).

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

638426880 is a wasteful number, since it uses less digits than its factorization.

638426880 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 86 (or 59 counting only the distinct ones).

The product of its (nonzero) digits is 442368, while the sum is 45.

The square root of 638426880 is about 25267.1106381399. The cubic root of 638426880 is about 861.0672166441.

The spelling of 638426880 in words is "six hundred thirty-eight million, four hundred twenty-six thousand, eight hundred eighty".