643553231 has 2 divisors, whose sum is σ = 643553232. Its totient is φ = 643553230.

The previous prime is 643553227. The next prime is 643553249. The reversal of 643553231 is 132355346.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 643553231 - 2² = 643553227 is a prime.

It is a super-2 number, since 2×643553231² = 828321522261078722, which contains 22 as substring.

It is a Sophie Germain prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (643553221) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321776615 + 321776616.

It is an arithmetic number, because the mean of its divisors is an integer number (321776616).

Almost surely, 2^643553231 is an apocalyptic number.

643553231 is a deficient number, since it is larger than the sum of its proper divisors (1).

643553231 is an equidigital number, since it uses as much as digits as its factorization.

643553231 is an evil number, because the sum of its binary digits is even.

The product of its digits is 32400, while the sum is 32.

The square root of 643553231 is about 25368.3509712397. The cubic root of 643553231 is about 863.3657678103.

The spelling of 643553231 in words is "six hundred forty-three million, five hundred fifty-three thousand, two hundred thirty-one".