21713265 has 112 divisors (see below), whose sum is σ = 47847168. Its totient is φ = 9237888.

The previous prime is 21713261. The next prime is 21713273. The reversal of 21713265 is 56231712.

It is a happy number.

It is not a de Polignac number, because 21713265 - 2² = 21713261 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

Its product of digits (2520) is a multiple of the sum of its prime factors (90).

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21713261) by changing a digit.

It is a polite number, since it can be written in 111 ways as a sum of consecutive naturals, for example, 586827 + ... + 586863.

Almost surely, 2^21713265 is an apocalyptic number.

It is an amenable number.

21713265 is an abundant number, since it is smaller than the sum of its proper divisors (26133903).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21713265 is an equidigital number, since it uses as much as digits as its factorization.

21713265 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 90 (or 75 counting only the distinct ones).

The product of its digits is 2520, while the sum is 27.

The square root of 21713265 is about 4659.7494567841. The cubic root of 21713265 is about 278.9812682533.

Adding to 21713265 its reverse (56231712), we get a palindrome (77944977).

The spelling of 21713265 in words is "twenty-one million, seven hundred thirteen thousand, two hundred sixty-five".