21387223 has 8 divisors (see below), whose sum is σ = 25126416. Its totient is φ = 17947200.

The previous prime is 21387203. The next prime is 21387227. The reversal of 21387223 is 32278312.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21387223 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21387191 and 21387200.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21387227) 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, 74638 + ... + 74923.

It is an arithmetic number, because the mean of its divisors is an integer number (3140802).

Almost surely, 2^21387223 is an apocalyptic number.

21387223 is a deficient number, since it is larger than the sum of its proper divisors (3739193).

21387223 is a wasteful number, since it uses less digits than its factorization.

21387223 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 149585.

The product of its digits is 4032, while the sum is 28.

The square root of 21387223 is about 4624.6322015918. The cubic root of 21387223 is about 277.5778446760.

The spelling of 21387223 in words is "twenty-one million, three hundred eighty-seven thousand, two hundred twenty-three".