21993223 has 16 divisors (see below), whose sum is σ = 27535680. Its totient is φ = 17127936.

The previous prime is 21993217. The next prime is 21993233. The reversal of 21993223 is 32239912.

It is a happy number.

It is not a de Polignac number, because 21993223 - 2¹³ = 21985031 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 (21993233) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 265 + ... + 6637.

It is an arithmetic number, because the mean of its divisors is an integer number (1720980).

Almost surely, 2^21993223 is an apocalyptic number.

21993223 is a deficient number, since it is larger than the sum of its proper divisors (5542457).

21993223 is a wasteful number, since it uses less digits than its factorization.

21993223 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6426.

The product of its digits is 5832, while the sum is 31.

The square root of 21993223 is about 4689.6932735521. The cubic root of 21993223 is about 280.1751582614.

The spelling of 21993223 in words is "twenty-one million, nine hundred ninety-three thousand, two hundred twenty-three".