638559161640 has 192 divisors, whose sum is σ = 2210349173760. Its totient is φ = 165680121600.

The previous prime is 638559161599. The next prime is 638559161641. The reversal of 638559161640 is 46161955836.

638559161640 is a `hidden beast` number, since 6 + 3 + 8 + 5 + 591 + 6 + 1 + 6 + 40 = 666.

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

It is not an unprimeable number, because it can be changed into a prime (638559161641) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 528136 + ... + 1247415.

It is an arithmetic number, because the mean of its divisors is an integer number (11512235280).

Almost surely, 2^638559161640 is an apocalyptic number.

638559161640 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

638559161640 is an abundant number, since it is smaller than the sum of its proper divisors (1571790012120).

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

638559161640 is a wasteful number, since it uses less digits than its factorization.

638559161640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1775614 (or 1775598 counting only the distinct ones).

The product of its (nonzero) digits is 4665600, while the sum is 54.

The spelling of 638559161640 in words is "six hundred thirty-eight billion, five hundred fifty-nine million, one hundred sixty-one thousand, six hundred forty".