21294223 has 4 divisors (see below), whose sum is σ = 21358888. Its totient is φ = 21229560.

The previous prime is 21294199. The next prime is 21294233. The reversal of 21294223 is 32249212.

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 21294223 - 2⁹ = 21293711 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21294233) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 31836 + ... + 32497.

It is an arithmetic number, because the mean of its divisors is an integer number (5339722).

Almost surely, 2^21294223 is an apocalyptic number.

21294223 is a deficient number, since it is larger than the sum of its proper divisors (64665).

21294223 is an equidigital number, since it uses as much as digits as its factorization.

21294223 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 64664.

The product of its digits is 1728, while the sum is 25.

The square root of 21294223 is about 4614.5663934979. The cubic root of 21294223 is about 277.1749211216.

The spelling of 21294223 in words is "twenty-one million, two hundred ninety-four thousand, two hundred twenty-three".