21726241 has 4 divisors (see below), whose sum is σ = 21773232. Its totient is φ = 21679252.

The previous prime is 21726233. The next prime is 21726247. The reversal of 21726241 is 14262712.

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 21726241 - 2³ = 21726233 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21726247) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 22795 + ... + 23728.

It is an arithmetic number, because the mean of its divisors is an integer number (5443308).

Almost surely, 2^21726241 is an apocalyptic number.

It is an amenable number.

21726241 is a deficient number, since it is larger than the sum of its proper divisors (46991).

21726241 is an equidigital number, since it uses as much as digits as its factorization.

21726241 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 46990.

The product of its digits is 1344, while the sum is 25.

The square root of 21726241 is about 4661.1415983641. The cubic root of 21726241 is about 279.0368309098.

Adding to 21726241 its reverse (14262712), we get a palindrome (35988953).

The spelling of 21726241 in words is "twenty-one million, seven hundred twenty-six thousand, two hundred forty-one".