638748550440 has 2048 divisors, whose sum is σ = 3045869568000. Its totient is φ = 115617300480.

The previous prime is 638748550381. The next prime is 638748550463. The reversal of 638748550440 is 44055847836.

It is a happy number.

638748550440 is a `hidden beast` number, since 6 + 3 + 8 + 7 + 48 + 550 + 4 + 40 = 666.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is an unprimeable number.

It is a polite number, since it can be written in 511 ways as a sum of consecutive naturals, for example, 2485402792 + ... + 2485403048.

It is an arithmetic number, because the mean of its divisors is an integer number (1487241000).

Almost surely, 2^638748550440 is an apocalyptic number.

638748550440 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 638748550440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1522934784000).

638748550440 is an abundant number, since it is smaller than the sum of its proper divisors (2407121017560).

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

638748550440 is a wasteful number, since it uses less digits than its factorization.

638748550440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 349 (or 317 counting only the distinct ones).

The product of its (nonzero) digits is 12902400, while the sum is 54.

The spelling of 638748550440 in words is "six hundred thirty-eight billion, seven hundred forty-eight million, five hundred fifty thousand, four hundred forty".