21284223 has 8 divisors (see below), whose sum is σ = 29612928. Its totient is φ = 13572504.

The previous prime is 21284189. The next prime is 21284227. The reversal of 21284223 is 32248212.

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

It is not a de Polignac number, because 21284223 - 2⁸ = 21283967 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21284193 and 21284202.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21284227) 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, 154165 + ... + 154302.

It is an arithmetic number, because the mean of its divisors is an integer number (3701616).

Almost surely, 2^21284223 is an apocalyptic number.

21284223 is a gapful number since it is divisible by the number (23) formed by its first and last digit.

21284223 is a deficient number, since it is larger than the sum of its proper divisors (8328705).

21284223 is a wasteful number, since it uses less digits than its factorization.

21284223 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 308493.

The product of its digits is 1536, while the sum is 24.

The square root of 21284223 is about 4613.4827408369. The cubic root of 21284223 is about 277.1315262032.

The spelling of 21284223 in words is "twenty-one million, two hundred eighty-four thousand, two hundred twenty-three".