643635331 has 2 divisors, whose sum is σ = 643635332. Its totient is φ = 643635330.

The previous prime is 643635323. The next prime is 643635341. The reversal of 643635331 is 133536346.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 643635331 - 2³ = 643635323 is a prime.

It is a super-2 number, since 2×643635331² = 828532878622959122, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (643635341) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321817665 + 321817666.

It is an arithmetic number, because the mean of its divisors is an integer number (321817666).

Almost surely, 2^643635331 is an apocalyptic number.

643635331 is a deficient number, since it is larger than the sum of its proper divisors (1).

643635331 is an equidigital number, since it uses as much as digits as its factorization.

643635331 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 58320, while the sum is 34.

The square root of 643635331 is about 25369.9690776319. The cubic root of 643635331 is about 863.4024802955.

The spelling of 643635331 in words is "six hundred forty-three million, six hundred thirty-five thousand, three hundred thirty-one".