638642880 has 336 divisors, whose sum is σ = 2343204864. Its totient is φ = 165473280.

The previous prime is 638642869. The next prime is 638642929. The reversal of 638642880 is 88246836.

It is a happy number.

638642880 is a `hidden beast` number, since 638 + 6 + 4 + 2 + 8 + 8 + 0 = 666.

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

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 3343585 + ... + 3343775.

It is an arithmetic number, because the mean of its divisors is an integer number (6973824).

Almost surely, 2^638642880 is an apocalyptic number.

638642880 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 638642880, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1171602432).

638642880 is an abundant number, since it is smaller than the sum of its proper divisors (1704561984).

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

638642880 is a wasteful number, since it uses less digits than its factorization.

638642880 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 266 (or 244 counting only the distinct ones).

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

The square root of 638642880 is about 25271.3846078920. The cubic root of 638642880 is about 861.1643144497.

The spelling of 638642880 in words is "six hundred thirty-eight million, six hundred forty-two thousand, eight hundred eighty".