638968840 has 32 divisors (see below), whose sum is σ = 1439055000. Its totient is φ = 255343104.

The previous prime is 638968823. The next prime is 638968849. The reversal of 638968840 is 48869836.

It can be written as a sum of positive squares in 4 ways, for example, as 521939716 + 117029124 = 22846^2 + 10818^2 .

It is not an unprimeable number, because it can be changed into a prime (638968849) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 38086 + ... + 52234.

Almost surely, 2^638968840 is an apocalyptic number.

It is an amenable number.

638968840 is an abundant number, since it is smaller than the sum of its proper divisors (800086160).

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

638968840 is a wasteful number, since it uses less digits than its factorization.

638968840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15289 (or 15285 counting only the distinct ones).

The product of its (nonzero) digits is 1990656, while the sum is 52.

The square root of 638968840 is about 25277.8329767407. The cubic root of 638968840 is about 861.3108007910.

The spelling of 638968840 in words is "six hundred thirty-eight million, nine hundred sixty-eight thousand, eight hundred forty".