21840265 has 4 divisors (see below), whose sum is σ = 26208324. Its totient is φ = 17472208.

The previous prime is 21840241. The next prime is 21840281. The reversal of 21840265 is 56204812.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 5607424 + 16232841 = 2368^2 + 4029^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21840265 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2184022 + ... + 2184031.

It is an arithmetic number, because the mean of its divisors is an integer number (6552081).

Almost surely, 2^21840265 is an apocalyptic number.

It is an amenable number.

21840265 is a deficient number, since it is larger than the sum of its proper divisors (4368059).

21840265 is an equidigital number, since it uses as much as digits as its factorization.

21840265 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4368058.

The product of its (nonzero) digits is 3840, while the sum is 28.

The square root of 21840265 is about 4673.3569305158. The cubic root of 21840265 is about 279.5241279175.

The spelling of 21840265 in words is "twenty-one million, eight hundred forty thousand, two hundred sixty-five".