421605643 has 2 divisors, whose sum is σ = 421605644. Its totient is φ = 421605642.

The previous prime is 421605637. The next prime is 421605647. The reversal of 421605643 is 346506124.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-421605643 is a prime.

It is not a weakly prime, because it can be changed into another prime (421605647) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 210802821 + 210802822.

It is an arithmetic number, because the mean of its divisors is an integer number (210802822).

Almost surely, 2^421605643 is an apocalyptic number.

421605643 is a deficient number, since it is larger than the sum of its proper divisors (1).

421605643 is an equidigital number, since it uses as much as digits as its factorization.

421605643 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 17280, while the sum is 31.

The square root of 421605643 is about 20533.0378414885. The cubic root of 421605643 is about 749.8403470540.

The spelling of 421605643 in words is "four hundred twenty-one million, six hundred five thousand, six hundred forty-three".