21565041 has 4 divisors (see below), whose sum is σ = 28753392. Its totient is φ = 14376692.

The previous prime is 21564989. The next prime is 21565073. The reversal of 21565041 is 14056512.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21565041 - 2²² = 17370737 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21565091) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3594171 + ... + 3594176.

It is an arithmetic number, because the mean of its divisors is an integer number (7188348).

Almost surely, 2^21565041 is an apocalyptic number.

It is an amenable number.

21565041 is a deficient number, since it is larger than the sum of its proper divisors (7188351).

21565041 is an equidigital number, since it uses as much as digits as its factorization.

21565041 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7188350.

The product of its (nonzero) digits is 1200, while the sum is 24.

The square root of 21565041 is about 4643.8175028741. The cubic root of 21565041 is about 278.3450032358.

It can be divided in two parts, 215 and 65041, that added together give a palindrome (65256).

The spelling of 21565041 in words is "twenty-one million, five hundred sixty-five thousand, forty-one".