638081808 has 240 divisors, whose sum is σ = 2163182976. Its totient is φ = 158146560.

The previous prime is 638081789. The next prime is 638081813. The reversal of 638081808 is 808180836.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is a self number, because there is not a number n which added to its sum of digits gives 638081808.

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, 964998 + ... + 965658.

Almost surely, 2^638081808 is an apocalyptic number.

638081808 is a gapful number since it is divisible by the number (68) 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 638081808, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1081591488).

638081808 is an abundant number, since it is smaller than the sum of its proper divisors (1525101168).

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

638081808 is a wasteful number, since it uses less digits than its factorization.

638081808 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 722 (or 703 counting only the distinct ones).

The product of its (nonzero) digits is 73728, while the sum is 42.

The square root of 638081808 is about 25260.2812335888. The cubic root of 638081808 is about 860.9120520537.

It can be divided in two parts, 6380 and 81808, that added together give a palindrome (88188).

The spelling of 638081808 in words is "six hundred thirty-eight million, eighty-one thousand, eight hundred eight".