21126252 has 144 divisors (see below), whose sum is σ = 63329280. Its totient is φ = 5443200.

The previous prime is 21126229. The next prime is 21126253. The reversal of 21126252 is 25262112.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is not an unprimeable number, because it can be changed into a prime (21126253) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 346302 + ... + 346362.

Almost surely, 2^21126252 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 21126252, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31664640).

21126252 is an abundant number, since it is smaller than the sum of its proper divisors (42203028).

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

21126252 is a wasteful number, since it uses less digits than its factorization.

21126252 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 132 (or 123 counting only the distinct ones).

The product of its digits is 480, while the sum is 21.

The square root of 21126252 is about 4596.3302753392. The cubic root of 21126252 is about 276.4442017406. Note that the first 3 decimals are identical.

Adding to 21126252 its reverse (25262112), we get a palindrome (46388364).

The spelling of 21126252 in words is "twenty-one million, one hundred twenty-six thousand, two hundred fifty-two".