641781979421 has 6 divisors (see below), whose sum is σ = 705429779166. Its totient is φ = 583438163000.

The previous prime is 641781979393. The next prime is 641781979441. The reversal of 641781979421 is 124979187146.

It can be written as a sum of positive squares in only one way, i.e., 578605156921 + 63176822500 = 760661^2 + 251350^2 .

It is not a de Polignac number, because 641781979421 - 2²⁶ = 641714870557 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (641781979441) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 2651991530 + ... + 2651991771.

It is an arithmetic number, because the mean of its divisors is an integer number (117571629861).

Almost surely, 2^641781979421 is an apocalyptic number.

It is an amenable number.

641781979421 is a deficient number, since it is larger than the sum of its proper divisors (63647799745).

641781979421 is a wasteful number, since it uses less digits than its factorization.

641781979421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5303983323 (or 5303983312 counting only the distinct ones).

The product of its digits is 6096384, while the sum is 59.

The spelling of 641781979421 in words is "six hundred forty-one billion, seven hundred eighty-one million, nine hundred seventy-nine thousand, four hundred twenty-one".