641221720 has 16 divisors (see below), whose sum is σ = 1442748960. Its totient is φ = 256488672.

The previous prime is 641221703. The next prime is 641221733. The reversal of 641221720 is 27122146.

It is a super-2 number, since 2×641221720² = 822330588399516800, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8015232 + ... + 8015311.

It is an arithmetic number, because the mean of its divisors is an integer number (90171810).

Almost surely, 2^641221720 is an apocalyptic number.

It is an amenable number.

641221720 is an abundant number, since it is smaller than the sum of its proper divisors (801527240).

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

641221720 is a wasteful number, since it uses less digits than its factorization.

641221720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16030554 (or 16030550 counting only the distinct ones).

The product of its (nonzero) digits is 1344, while the sum is 25.

The square root of 641221720 is about 25322.3561305025. The cubic root of 641221720 is about 862.3218849451.

Adding to 641221720 its reverse (27122146), we get a palindrome (668343866).

The spelling of 641221720 in words is "six hundred forty-one million, two hundred twenty-one thousand, seven hundred twenty".