643624427 has 2 divisors, whose sum is σ = 643624428. Its totient is φ = 643624426.

The previous prime is 643624381. The next prime is 643624453. The reversal of 643624427 is 724426346.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 643624427 - 2¹² = 643620331 is a prime.

It is not a weakly prime, because it can be changed into another prime (643624477) 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 as a sum of consecutive naturals, namely, 321812213 + 321812214.

It is an arithmetic number, because the mean of its divisors is an integer number (321812214).

Almost surely, 2^643624427 is an apocalyptic number.

643624427 is a deficient number, since it is larger than the sum of its proper divisors (1).

643624427 is an equidigital number, since it uses as much as digits as its factorization.

643624427 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 193536, while the sum is 38.

The square root of 643624427 is about 25369.7541769722. The cubic root of 643624427 is about 863.3976045565.

The spelling of 643624427 in words is "six hundred forty-three million, six hundred twenty-four thousand, four hundred twenty-seven".