641555772 has 72 divisors (see below), whose sum is σ = 1768394880. Its totient is φ = 179449920.

The previous prime is 641555731. The next prime is 641555773. The reversal of 641555772 is 277555146.

It is a happy number.

It is a hoax number, since the sum of its digits (42) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (641555773) by changing a digit.

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 23 ways as a sum of consecutive naturals, for example, 7929 + ... + 36687.

It is an arithmetic number, because the mean of its divisors is an integer number (24561040).

Almost surely, 2^641555772 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 641555772, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (884197440).

641555772 is an abundant number, since it is smaller than the sum of its proper divisors (1126839108).

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

641555772 is a wasteful number, since it uses less digits than its factorization.

641555772 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 28803 (or 28788 counting only the distinct ones).

The product of its digits is 294000, while the sum is 42.

The square root of 641555772 is about 25328.9512613531. The cubic root of 641555772 is about 862.4716045262.

The spelling of 641555772 in words is "six hundred forty-one million, five hundred fifty-five thousand, seven hundred seventy-two".