638985220 has 24 divisors (see below), whose sum is σ = 1354901184. Its totient is φ = 253111776.

The previous prime is 638985197. The next prime is 638985223. The reversal of 638985220 is 22589836.

It is a super-2 number, since 2×638985220² = 816604222756896800, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (638985223) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 153034 + ... + 157153.

It is an arithmetic number, because the mean of its divisors is an integer number (56454216).

Almost surely, 2^638985220 is an apocalyptic number.

It is an amenable number.

638985220 is an abundant number, since it is smaller than the sum of its proper divisors (715915964).

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

638985220 is a wasteful number, since it uses less digits than its factorization.

638985220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 310299 (or 310297 counting only the distinct ones).

The product of its (nonzero) digits is 207360, while the sum is 43.

The square root of 638985220 is about 25278.1569739568. The cubic root of 638985220 is about 861.3181606441.

The spelling of 638985220 in words is "six hundred thirty-eight million, nine hundred eighty-five thousand, two hundred twenty".