21513852 has 72 divisors (see below), whose sum is σ = 58181760. Its totient is φ = 6683040.

The previous prime is 21513851. The next prime is 21513859. The reversal of 21513852 is 25831512.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21513851) 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 23 ways as a sum of consecutive naturals, for example, 48343 + ... + 48785.

It is an arithmetic number, because the mean of its divisors is an integer number (808080).

Almost surely, 2^21513852 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 21513852, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29090880).

21513852 is an abundant number, since it is smaller than the sum of its proper divisors (36667908).

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

21513852 is a wasteful number, since it uses less digits than its factorization.

21513852 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 543 (or 538 counting only the distinct ones).

The product of its digits is 2400, while the sum is 27.

The square root of 21513852 is about 4638.3027068099. The cubic root of 21513852 is about 278.1245926350.

The spelling of 21513852 in words is "twenty-one million, five hundred thirteen thousand, eight hundred fifty-two".