21643411 has 2 divisors, whose sum is σ = 21643412. Its totient is φ = 21643410.

The previous prime is 21643403. The next prime is 21643421. The reversal of 21643411 is 11434612.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21643411 - 2³ = 21643403 is a prime.

It is not a weakly prime, because it can be changed into another prime (21643421) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10821705 + 10821706.

It is an arithmetic number, because the mean of its divisors is an integer number (10821706).

Almost surely, 2^21643411 is an apocalyptic number.

21643411 is a deficient number, since it is larger than the sum of its proper divisors (1).

21643411 is an equidigital number, since it uses as much as digits as its factorization.

21643411 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 576, while the sum is 22.

The square root of 21643411 is about 4652.2479512597. The cubic root of 21643411 is about 278.6817755506.

The spelling of 21643411 in words is "twenty-one million, six hundred forty-three thousand, four hundred eleven".