21097224 has 48 divisors (see below), whose sum is σ = 57957120. Its totient is φ = 6931680.

The previous prime is 21097217. The next prime is 21097229. The reversal of 21097224 is 42279012.

It is a hoax number, since the sum of its digits (27) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (21097229) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 3049 + ... + 7175.

It is an arithmetic number, because the mean of its divisors is an integer number (1207440).

Almost surely, 2^21097224 is an apocalyptic number.

21097224 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21097224, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28978560).

21097224 is an abundant number, since it is smaller than the sum of its proper divisors (36859896).

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

21097224 is a wasteful number, since it uses less digits than its factorization.

21097224 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4210 (or 4203 counting only the distinct ones).

The product of its (nonzero) digits is 2016, while the sum is 27.

The square root of 21097224 is about 4593.1714533642. The cubic root of 21097224 is about 276.3175299511.

It can be divided in two parts, 21097 and 224, that added together give a triangular number (21321 = T₂₀₆).

The spelling of 21097224 in words is "twenty-one million, ninety-seven thousand, two hundred twenty-four".