421643309 has 2 divisors, whose sum is σ = 421643310. Its totient is φ = 421643308.

The previous prime is 421643297. The next prime is 421643353. The reversal of 421643309 is 903346124.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 421480900 + 162409 = 20530^2 + 403^2 .

It is a cyclic number.

It is not a de Polignac number, because 421643309 - 2¹² = 421639213 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (421648309) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 210821654 + 210821655.

It is an arithmetic number, because the mean of its divisors is an integer number (210821655).

Almost surely, 2^421643309 is an apocalyptic number.

It is an amenable number.

421643309 is a deficient number, since it is larger than the sum of its proper divisors (1).

421643309 is an equidigital number, since it uses as much as digits as its factorization.

421643309 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 15552, while the sum is 32.

The square root of 421643309 is about 20533.9550257616. The cubic root of 421643309 is about 749.8626764875.

The spelling of 421643309 in words is "four hundred twenty-one million, six hundred forty-three thousand, three hundred nine".