643504831 has 2 divisors, whose sum is σ = 643504832. Its totient is φ = 643504830.

The previous prime is 643504819. The next prime is 643504837. The reversal of 643504831 is 138405346.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 643504831 - 2⁹ = 643504319 is a prime.

It is a super-2 number, since 2×643504831² = 828196935040677122, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (643504837) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321752415 + 321752416.

It is an arithmetic number, because the mean of its divisors is an integer number (321752416).

Almost surely, 2^643504831 is an apocalyptic number.

643504831 is a deficient number, since it is larger than the sum of its proper divisors (1).

643504831 is an equidigital number, since it uses as much as digits as its factorization.

643504831 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 34560, while the sum is 34.

The square root of 643504831 is about 25367.3970087591. The cubic root of 643504831 is about 863.3441234206.

The spelling of 643504831 in words is "six hundred forty-three million, five hundred four thousand, eight hundred thirty-one".