21993224 has 16 divisors (see below), whose sum is σ = 44986320. Its totient is φ = 9996880.

The previous prime is 21993217. The next prime is 21993233. The reversal of 21993224 is 42239912.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 124874 + ... + 125049.

It is an arithmetic number, because the mean of its divisors is an integer number (2811645).

Almost surely, 2^21993224 is an apocalyptic number.

It is an amenable number.

21993224 is an abundant number, since it is smaller than the sum of its proper divisors (22993096).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21993224 is a wasteful number, since it uses less digits than its factorization.

21993224 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 249940 (or 249936 counting only the distinct ones).

The product of its digits is 7776, while the sum is 32.

The square root of 21993224 is about 4689.6933801689. The cubic root of 21993224 is about 280.1751625078.

The spelling of 21993224 in words is "twenty-one million, nine hundred ninety-three thousand, two hundred twenty-four".