21909263 has 2 divisors, whose sum is σ = 21909264. Its totient is φ = 21909262.

The previous prime is 21909259. The next prime is 21909269. The reversal of 21909263 is 36290912.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21909263 - 2² = 21909259 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21909269) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10954631 + 10954632.

It is an arithmetic number, because the mean of its divisors is an integer number (10954632).

Almost surely, 2^21909263 is an apocalyptic number.

21909263 is a deficient number, since it is larger than the sum of its proper divisors (1).

21909263 is an equidigital number, since it uses as much as digits as its factorization.

21909263 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 5832, while the sum is 32.

The square root of 21909263 is about 4680.7331690666. The cubic root of 21909263 is about 279.8181770236.

The spelling of 21909263 in words is "twenty-one million, nine hundred nine thousand, two hundred sixty-three".