641566657 has 2 divisors, whose sum is σ = 641566658. Its totient is φ = 641566656.

The previous prime is 641566631. The next prime is 641566687. The reversal of 641566657 is 756665146.

641566657 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., 523540161 + 118026496 = 22881^2 + 10864^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-641566657 is a prime.

It is a super-4 number, since 4×641566657⁴ (a number of 36 digits) contains 4444 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (641566687) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320783328 + 320783329.

It is an arithmetic number, because the mean of its divisors is an integer number (320783329).

Almost surely, 2^641566657 is an apocalyptic number.

It is an amenable number.

641566657 is a deficient number, since it is larger than the sum of its proper divisors (1).

641566657 is an equidigital number, since it uses as much as digits as its factorization.

641566657 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 907200, while the sum is 46.

The square root of 641566657 is about 25329.1661331359. The cubic root of 641566657 is about 862.4764822265.

The spelling of 641566657 in words is "six hundred forty-one million, five hundred sixty-six thousand, six hundred fifty-seven".