21265909 has 8 divisors (see below), whose sum is σ = 24336000. Its totient is φ = 18203856.

The previous prime is 21265897. The next prime is 21265913. The reversal of 21265909 is 90956212.

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 21265909 - 2⁵ = 21265877 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21265999) 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, 5592 + ... + 8590.

It is an arithmetic number, because the mean of its divisors is an integer number (3042000).

Almost surely, 2^21265909 is an apocalyptic number.

It is an amenable number.

21265909 is a deficient number, since it is larger than the sum of its proper divisors (3070091).

21265909 is a wasteful number, since it uses less digits than its factorization.

21265909 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4019.

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

The square root of 21265909 is about 4611.4974791276. The cubic root of 21265909 is about 277.0520174959.

The spelling of 21265909 in words is "twenty-one million, two hundred sixty-five thousand, nine hundred nine".