21265905 has 8 divisors (see below), whose sum is σ = 34025472. Its totient is φ = 11341808.

The previous prime is 21265897. The next prime is 21265913. The reversal of 21265905 is 50956212.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21265897) and next prime (21265913).

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 21265905 - 2³ = 21265897 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 708849 + ... + 708878.

It is an arithmetic number, because the mean of its divisors is an integer number (4253184).

Almost surely, 2^21265905 is an apocalyptic number.

It is an amenable number.

21265905 is a deficient number, since it is larger than the sum of its proper divisors (12759567).

21265905 is a wasteful number, since it uses less digits than its factorization.

21265905 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1417735.

The product of its (nonzero) digits is 5400, while the sum is 30.

The square root of 21265905 is about 4611.4970454290. The cubic root of 21265905 is about 277.0520001252.

The spelling of 21265905 in words is "twenty-one million, two hundred sixty-five thousand, nine hundred five".