21744121 has 8 divisors (see below), whose sum is σ = 25258304. Its totient is φ = 18331920.

The previous prime is 21744119. The next prime is 21744137. The reversal of 21744121 is 12144712.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21744121 - 2¹ = 21744119 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21744092 and 21744101.

It is not an unprimeable number, because it can be changed into a prime (21744101) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 25035 + ... + 25888.

It is an arithmetic number, because the mean of its divisors is an integer number (3157288).

Almost surely, 2^21744121 is an apocalyptic number.

It is an amenable number.

21744121 is a deficient number, since it is larger than the sum of its proper divisors (3514183).

21744121 is an equidigital number, since it uses as much as digits as its factorization.

21744121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 50991.

The product of its digits is 448, while the sum is 22.

The square root of 21744121 is about 4663.0591889874. The cubic root of 21744121 is about 279.1133560439.

Adding to 21744121 its reverse (12144712), we get a palindrome (33888833).

The spelling of 21744121 in words is "twenty-one million, seven hundred forty-four thousand, one hundred twenty-one".