638994949740 has 360 divisors, whose sum is σ = 2468995784640. Its totient is φ = 137464169472.

The previous prime is 638994949609. The next prime is 638994949781. The reversal of 638994949740 is 47949499836.

638994949740 is a `hidden beast` number, since 6 + 3 + 8 + 9 + 9 + 494 + 97 + 40 = 666.

It is a Smith number, since the sum of its digits (72) coincides with the sum of the digits of its prime factors.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 119 ways as a sum of consecutive naturals, for example, 1112701 + ... + 1586219.

It is an arithmetic number, because the mean of its divisors is an integer number (6858321624).

Almost surely, 2^638994949740 is an apocalyptic number.

638994949740 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 638994949740, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1234497892320).

638994949740 is an abundant number, since it is smaller than the sum of its proper divisors (1830000834900).

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

638994949740 is a wasteful number, since it uses less digits than its factorization.

638994949740 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 473571 (or 473553 counting only the distinct ones).

The product of its (nonzero) digits is 423263232, while the sum is 72.

The spelling of 638994949740 in words is "six hundred thirty-eight billion, nine hundred ninety-four million, nine hundred forty-nine thousand, seven hundred forty".