641521660 has 24 divisors (see below), whose sum is σ = 1450826496. Its totient is φ = 236869440.

The previous prime is 641521631. The next prime is 641521667. The reversal of 641521660 is 66125146.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (641521667) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1233436 + ... + 1233955.

It is an arithmetic number, because the mean of its divisors is an integer number (60451104).

Almost surely, 2^641521660 is an apocalyptic number.

It is an amenable number.

641521660 is an abundant number, since it is smaller than the sum of its proper divisors (809304836).

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

641521660 is a wasteful number, since it uses less digits than its factorization.

641521660 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2467413 (or 2467411 counting only the distinct ones).

The product of its (nonzero) digits is 8640, while the sum is 31.

The square root of 641521660 is about 25328.2778727651. The cubic root of 641521660 is about 862.4563181686.

The spelling of 641521660 in words is "six hundred forty-one million, five hundred twenty-one thousand, six hundred sixty".