641806943 has 2 divisors, whose sum is σ = 641806944. Its totient is φ = 641806942.

The previous prime is 641806939. The next prime is 641806987. The reversal of 641806943 is 349608146.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 641806943 - 2² = 641806939 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 641806943.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (641806903) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320903471 + 320903472.

It is an arithmetic number, because the mean of its divisors is an integer number (320903472).

Almost surely, 2^641806943 is an apocalyptic number.

641806943 is a deficient number, since it is larger than the sum of its proper divisors (1).

641806943 is an equidigital number, since it uses as much as digits as its factorization.

641806943 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 124416, while the sum is 41.

The square root of 641806943 is about 25333.9089561797. The cubic root of 641806943 is about 862.5841432437.

The spelling of 641806943 in words is "six hundred forty-one million, eight hundred six thousand, nine hundred forty-three".