21999224 has 64 divisors (see below), whose sum is σ = 49170240. Its totient is φ = 9123840.

The previous prime is 21999221. The next prime is 21999269. The reversal of 21999224 is 42299912.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21999221) 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, 40394 + ... + 40934.

It is an arithmetic number, because the mean of its divisors is an integer number (768285).

Almost surely, 2^21999224 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21999224, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24585120).

21999224 is an abundant number, since it is smaller than the sum of its proper divisors (27171016).

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

21999224 is a wasteful number, since it uses less digits than its factorization.

21999224 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 600 (or 596 counting only the distinct ones).

The product of its digits is 23328, while the sum is 38.

The square root of 21999224 is about 4690.3330372160. Note that the first 3 decimals coincide. The cubic root of 21999224 is about 280.2006385078.

The spelling of 21999224 in words is "twenty-one million, nine hundred ninety-nine thousand, two hundred twenty-four".