21130524 has 72 divisors (see below), whose sum is σ = 58280880. Its totient is φ = 6619392.

The previous prime is 21130511. The next prime is 21130573. The reversal of 21130524 is 42503112.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a junction number, because it is equal to n+sod(n) for n = 21130497 and 21130506.

It is a congruent number.

It is an unprimeable number.

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, 30874 + ... + 31550.

Almost surely, 2^21130524 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 21130524, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29140440).

21130524 is an abundant number, since it is smaller than the sum of its proper divisors (37150356).

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

21130524 is a wasteful number, since it uses less digits than its factorization.

21130524 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 724 (or 699 counting only the distinct ones).

The product of its (nonzero) digits is 240, while the sum is 18.

The square root of 21130524 is about 4596.7949704114. The cubic root of 21130524 is about 276.4628340097.

Adding to 21130524 its reverse (42503112), we get a palindrome (63633636).

The spelling of 21130524 in words is "twenty-one million, one hundred thirty thousand, five hundred twenty-four".