641666431 has 4 divisors (see below), whose sum is σ = 733333072. Its totient is φ = 549999792.

The previous prime is 641666429. The next prime is 641666447. The reversal of 641666431 is 134666146.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 641666431 - 2¹ = 641666429 is a prime.

It is a super-2 number, since 2×641666431² = 823471617344555522, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (641666401) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 45833310 + ... + 45833323.

It is an arithmetic number, because the mean of its divisors is an integer number (183333268).

Almost surely, 2^641666431 is an apocalyptic number.

641666431 is a deficient number, since it is larger than the sum of its proper divisors (91666641).

641666431 is an equidigital number, since it uses as much as digits as its factorization.

641666431 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 91666640.

The product of its digits is 62208, while the sum is 37.

The square root of 641666431 is about 25331.1356042322. The cubic root of 641666431 is about 862.5211895935.

The spelling of 641666431 in words is "six hundred forty-one million, six hundred sixty-six thousand, four hundred thirty-one".