641781979441 has 2 divisors, whose sum is σ = 641781979442. Its totient is φ = 641781979440.

The previous prime is 641781979393. The next prime is 641781979457. The reversal of 641781979441 is 144979187146.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 640224019600 + 1557959841 = 800140^2 + 39471^2 .

It is a cyclic number.

It is not a de Polignac number, because 641781979441 - 2¹⁷ = 641781848369 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 641781979441.

It is not a weakly prime, because it can be changed into another prime (641781979141) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320890989720 + 320890989721.

It is an arithmetic number, because the mean of its divisors is an integer number (320890989721).

Almost surely, 2^641781979441 is an apocalyptic number.

It is an amenable number.

641781979441 is a deficient number, since it is larger than the sum of its proper divisors (1).

641781979441 is an equidigital number, since it uses as much as digits as its factorization.

641781979441 is an evil number, because the sum of its binary digits is even.

The product of its digits is 12192768, while the sum is 61.

The spelling of 641781979441 in words is "six hundred forty-one billion, seven hundred eighty-one million, nine hundred seventy-nine thousand, four hundred forty-one".