21990224 has 20 divisors (see below), whose sum is σ = 42714900. Its totient is φ = 10967040.

The previous prime is 21990193. The next prime is 21990257. The reversal of 21990224 is 42209912.

It can be written as a sum of positive squares in 2 ways, for example, as 17909824 + 4080400 = 4232^2 + 2020^2 .

It is a hoax number, since the sum of its digits (29) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

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, 5654 + ... + 8714.

It is an arithmetic number, because the mean of its divisors is an integer number (2135745).

Almost surely, 2^21990224 is an apocalyptic number.

It is an amenable number.

21990224 is a deficient number, since it is larger than the sum of its proper divisors (20724676).

21990224 is a wasteful number, since it uses less digits than its factorization.

21990224 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3518 (or 3512 counting only the distinct ones).

The product of its (nonzero) digits is 2592, while the sum is 29.

The square root of 21990224 is about 4689.3735189255. The cubic root of 21990224 is about 280.1624227702.

The spelling of 21990224 in words is "twenty-one million, nine hundred ninety thousand, two hundred twenty-four".