641221621 has 2 divisors, whose sum is σ = 641221622. Its totient is φ = 641221620.

The previous prime is 641221597. The next prime is 641221687. The reversal of 641221621 is 126122146.

It is a happy number.

641221621 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 597264721 + 43956900 = 24439^2 + 6630^2 .

It is a cyclic number.

It is not a de Polignac number, because 641221621 - 2⁹ = 641221109 is a prime.

It is a super-2 number, since 2×641221621² = 822330334475735282, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (641221121) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320610810 + 320610811.

It is an arithmetic number, because the mean of its divisors is an integer number (320610811).

Almost surely, 2^641221621 is an apocalyptic number.

It is an amenable number.

641221621 is a deficient number, since it is larger than the sum of its proper divisors (1).

641221621 is an equidigital number, since it uses as much as digits as its factorization.

641221621 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1152, while the sum is 25.

The square root of 641221621 is about 25322.3541757081. The cubic root of 641221621 is about 862.3218405663.

Adding to 641221621 its reverse (126122146), we get a palindrome (767343767).

The spelling of 641221621 in words is "six hundred forty-one million, two hundred twenty-one thousand, six hundred twenty-one".