643566431 has 2 divisors, whose sum is σ = 643566432. Its totient is φ = 643566430.

The previous prime is 643566421. The next prime is 643566449. The reversal of 643566431 is 134665346.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 643566431 - 2¹⁸ = 643304287 is a prime.

It is a super-2 number, since 2×643566431² = 828355502220155522, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (643566421) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321783215 + 321783216.

It is an arithmetic number, because the mean of its divisors is an integer number (321783216).

Almost surely, 2^643566431 is an apocalyptic number.

643566431 is a deficient number, since it is larger than the sum of its proper divisors (1).

643566431 is an equidigital number, since it uses as much as digits as its factorization.

643566431 is an evil number, because the sum of its binary digits is even.

The product of its digits is 155520, while the sum is 38.

The square root of 643566431 is about 25368.6111365995. The cubic root of 643566431 is about 863.3716706373.

The spelling of 643566431 in words is "six hundred forty-three million, five hundred sixty-six thousand, four hundred thirty-one".