21224100 has 72 divisors (see below), whose sum is σ = 61871040. Its totient is φ = 5617280.

The previous prime is 21224087. The next prime is 21224123. The reversal of 21224100 is 142212.

It is a Harshad number since it is a multiple of its sum of digits (12).

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 78766 + ... + 79034.

It is an arithmetic number, because the mean of its divisors is an integer number (859320).

Almost surely, 2^21224100 is an apocalyptic number.

21224100 is a gapful number since it is divisible by the number (20) 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 21224100, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30935520).

21224100 is an abundant number, since it is smaller than the sum of its proper divisors (40646940).

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

21224100 is a wasteful number, since it uses less digits than its factorization.

21224100 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 549 (or 542 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 12.

The square root of 21224100 is about 4606.9621227008. The cubic root of 21224100 is about 276.8703359911.

Adding to 21224100 its reverse (142212), we get a palindrome (21366312).

The spelling of 21224100 in words is "twenty-one million, two hundred twenty-four thousand, one hundred".