641785961 has 2 divisors, whose sum is σ = 641785962. Its totient is φ = 641785960.

The previous prime is 641785943. The next prime is 641785981. The reversal of 641785961 is 169587146.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 641355625 + 430336 = 25325^2 + 656^2 .

It is a cyclic number.

It is not a de Polignac number, because 641785961 - 2¹⁰ = 641784937 is a prime.

It is not a weakly prime, because it can be changed into another prime (641785981) by changing a digit.

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 as a sum of consecutive naturals, namely, 320892980 + 320892981.

It is an arithmetic number, because the mean of its divisors is an integer number (320892981).

Almost surely, 2^641785961 is an apocalyptic number.

It is an amenable number.

641785961 is a deficient number, since it is larger than the sum of its proper divisors (1).

641785961 is an equidigital number, since it uses as much as digits as its factorization.

641785961 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 362880, while the sum is 47.

The square root of 641785961 is about 25333.4948437834. The cubic root of 641785961 is about 862.5747432531.

The spelling of 641785961 in words is "six hundred forty-one million, seven hundred eighty-five thousand, nine hundred sixty-one".