638412818640 has 160 divisors (see below), whose sum is σ = 2044824051456. Its totient is φ = 164678492160.

The previous prime is 638412818629. The next prime is 638412818647. The reversal of 638412818640 is 46818214836.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (638412818647) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 549672 + ... + 1256568.

Almost surely, 2^638412818640 is an apocalyptic number.

638412818640 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 638412818640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1022412025728).

638412818640 is an abundant number, since it is smaller than the sum of its proper divisors (1406411232816).

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

638412818640 is a wasteful number, since it uses less digits than its factorization.

638412818640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 707037 (or 707031 counting only the distinct ones).

The product of its (nonzero) digits is 1769472, while the sum is 51.

The spelling of 638412818640 in words is "six hundred thirty-eight billion, four hundred twelve million, eight hundred eighteen thousand, six hundred forty".