641931840 has 336 divisors, whose sum is σ = 2516282496. Its totient is φ = 148684800.

The previous prime is 641931839. The next prime is 641931887. The reversal of 641931840 is 48139146.

641931840 is a `hidden beast` number, since 641 + 9 + 3 + 1 + 8 + 4 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 641931795 and 641931804.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 728200 + ... + 729080.

It is an arithmetic number, because the mean of its divisors is an integer number (7488936).

Almost surely, 2^641931840 is an apocalyptic number.

641931840 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 641931840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1258141248).

641931840 is an abundant number, since it is smaller than the sum of its proper divisors (1874350656).

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

641931840 is a wasteful number, since it uses less digits than its factorization.

641931840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 938 (or 925 counting only the distinct ones).

The product of its (nonzero) digits is 20736, while the sum is 36.

The square root of 641931840 is about 25336.3738526254. The cubic root of 641931840 is about 862.6400931859.

The spelling of 641931840 in words is "six hundred forty-one million, nine hundred thirty-one thousand, eight hundred forty".