641166391 has 2 divisors, whose sum is σ = 641166392. Its totient is φ = 641166390.

The previous prime is 641166389. The next prime is 641166437. The reversal of 641166391 is 193661146.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 641166391 - 2¹ = 641166389 is a prime.

It is a super-2 number, since 2×641166391² = 822188681895929762, which contains 22 as substring.

Together with 641166389, it forms a pair of twin primes.

It is a self number, because there is not a number n which added to its sum of digits gives 641166391.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (641167391) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320583195 + 320583196.

It is an arithmetic number, because the mean of its divisors is an integer number (320583196).

Almost surely, 2^641166391 is an apocalyptic number.

641166391 is a deficient number, since it is larger than the sum of its proper divisors (1).

641166391 is an equidigital number, since it uses as much as digits as its factorization.

641166391 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 23328, while the sum is 37.

The square root of 641166391 is about 25321.2636138088. The cubic root of 641166391 is about 862.2970818864.

It can be divided in two parts, 64116 and 6391, that added together give a palindrome (70507).

The spelling of 641166391 in words is "six hundred forty-one million, one hundred sixty-six thousand, three hundred ninety-one".