21909265 has 8 divisors (see below), whose sum is σ = 30047040. Its totient is φ = 15023472.

The previous prime is 21909263. The next prime is 21909269. The reversal of 21909265 is 56290912.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21909265 - 2¹ = 21909263 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21909265.

It is not an unprimeable number, because it can be changed into a prime (21909263) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 312955 + ... + 313024.

It is an arithmetic number, because the mean of its divisors is an integer number (3755880).

Almost surely, 2^21909265 is an apocalyptic number.

It is an amenable number.

21909265 is a deficient number, since it is larger than the sum of its proper divisors (8137775).

21909265 is an equidigital number, since it uses as much as digits as its factorization.

21909265 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 625991.

The product of its (nonzero) digits is 9720, while the sum is 34.

The square root of 21909265 is about 4680.7333827083. The cubic root of 21909265 is about 279.8181855381.

The spelling of 21909265 in words is "twenty-one million, nine hundred nine thousand, two hundred sixty-five".