638920020 has 24 divisors (see below), whose sum is σ = 1788976224. Its totient is φ = 170378656.

The previous prime is 638919991. The next prime is 638920057. The reversal of 638920020 is 20029836.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a self number, because there is not a number n which added to its sum of digits gives 638920020.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5324274 + ... + 5324393.

It is an arithmetic number, because the mean of its divisors is an integer number (74540676).

Almost surely, 2^638920020 is an apocalyptic number.

638920020 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

638920020 is an abundant number, since it is smaller than the sum of its proper divisors (1150056204).

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

638920020 is a wasteful number, since it uses less digits than its factorization.

638920020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10648679 (or 10648677 counting only the distinct ones).

The product of its (nonzero) digits is 5184, while the sum is 30.

The square root of 638920020 is about 25276.8672900737. The cubic root of 638920020 is about 861.2888642679.

Adding to 638920020 its reverse (20029836), we get a palindrome (658949856).

The spelling of 638920020 in words is "six hundred thirty-eight million, nine hundred twenty thousand, twenty".