641388440 has 192 divisors, whose sum is σ = 1861574400. Its totient is φ = 196627200.

The previous prime is 641388431. The next prime is 641388479. The reversal of 641388440 is 44883146.

It is a super-2 number, since 2×641388440² = 822758261931267200, which contains 22 as substring.

It is a hoax number, since the sum of its digits (38) coincides with the sum of the digits of its distinct prime factors.

It is a junction number, because it is equal to n+sod(n) for n = 641388394 and 641388403.

It is a congruent number.

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, 1530551 + ... + 1530969.

It is an arithmetic number, because the mean of its divisors is an integer number (9695700).

Almost surely, 2^641388440 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 641388440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (930787200).

641388440 is an abundant number, since it is smaller than the sum of its proper divisors (1220185960).

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

641388440 is a wasteful number, since it uses less digits than its factorization.

641388440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 526 (or 515 counting only the distinct ones).

The product of its (nonzero) digits is 73728, while the sum is 38.

The square root of 641388440 is about 25325.6478693044. The cubic root of 641388440 is about 862.3966140869.

The spelling of 641388440 in words is "six hundred forty-one million, three hundred eighty-eight thousand, four hundred forty".