21516252 has 24 divisors (see below), whose sum is σ = 50393616. Its totient is φ = 7145088.

The previous prime is 21516241. The next prime is 21516259. The reversal of 21516252 is 25261512.

It is a happy number.

It is a zygodrome in base 9.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21516259) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 88 + ... + 6560.

It is an arithmetic number, because the mean of its divisors is an integer number (2099734).

Almost surely, 2^21516252 is an apocalyptic number.

It is an amenable number.

21516252 is an abundant number, since it is smaller than the sum of its proper divisors (28877364).

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

21516252 is a wasteful number, since it uses less digits than its factorization.

21516252 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6757 (or 6755 counting only the distinct ones).

The product of its digits is 1200, while the sum is 24.

The square root of 21516252 is about 4638.5614149217. The cubic root of 21516252 is about 278.1349344093.

Adding to 21516252 its reverse (25261512), we get a palindrome (46777764).

The spelling of 21516252 in words is "twenty-one million, five hundred sixteen thousand, two hundred fifty-two".