21744427 has 4 divisors (see below), whose sum is σ = 21764440. Its totient is φ = 21724416.

The previous prime is 21744421. The next prime is 21744431. The reversal of 21744427 is 72444712.

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

It is a cyclic number.

It is not a de Polignac number, because 21744427 - 2¹¹ = 21742379 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21744421) 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, 8277 + ... + 10582.

It is an arithmetic number, because the mean of its divisors is an integer number (5441110).

Almost surely, 2^21744427 is an apocalyptic number.

21744427 is a deficient number, since it is larger than the sum of its proper divisors (20013).

21744427 is a wasteful number, since it uses less digits than its factorization.

21744427 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20012.

The product of its digits is 12544, while the sum is 31.

The square root of 21744427 is about 4663.0919999502. The cubic root of 21744427 is about 279.1146653370.

It can be divided in two parts, 217 and 44427, that added together give a palindrome (44644).

The spelling of 21744427 in words is "twenty-one million, seven hundred forty-four thousand, four hundred twenty-seven".