641811556 has 27 divisors (see below), whose sum is σ = 1149571801. Its totient is φ = 313533584.

The previous prime is 641811517. The next prime is 641811601. The reversal of 641811556 is 655118146.

The square root of 641811556 is 25334.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 462680100 + 179131456 = 21510^2 + 13384^2 .

It is a super-2 number, since 2×641811556² = 823844146830282272, which contains 22 as substring.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 2685285 + ... + 2685523.

Almost surely, 2^641811556 is an apocalyptic number.

641811556 is the 25334-th square number.

It is an amenable number.

641811556 is a deficient number, since it is larger than the sum of its proper divisors (507760245).

641811556 is an equidigital number, since it uses as much as digits as its factorization.

641811556 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 588 (or 294 counting only the distinct ones).

The product of its digits is 28800, while the sum is 37.

The cubic root of 641811556 is about 862.5862098522.

The spelling of 641811556 in words is "six hundred forty-one million, eight hundred eleven thousand, five hundred fifty-six".