21744641 has 4 divisors (see below), whose sum is σ = 22332372. Its totient is φ = 21156912.

The previous prime is 21744631. The next prime is 21744727. The reversal of 21744641 is 14644712.

It is a happy number.

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 14984641 + 6760000 = 3871^2 + 2600^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21744641 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21744631) 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, 293810 + ... + 293883.

It is an arithmetic number, because the mean of its divisors is an integer number (5583093).

Almost surely, 2^21744641 is an apocalyptic number.

It is an amenable number.

21744641 is a deficient number, since it is larger than the sum of its proper divisors (587731).

21744641 is an equidigital number, since it uses as much as digits as its factorization.

21744641 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 587730.

The product of its digits is 5376, while the sum is 29.

The square root of 21744641 is about 4663.1149460420. The cubic root of 21744641 is about 279.1155809792.

The spelling of 21744641 in words is "twenty-one million, seven hundred forty-four thousand, six hundred forty-one".