21213524 has 12 divisors (see below), whose sum is σ = 37161684. Its totient is φ = 10595904.

The previous prime is 21213487. The next prime is 21213553. The reversal of 21213524 is 42531212.

It can be written as a sum of positive squares in 2 ways, for example, as 5373124 + 15840400 = 2318^2 + 3980^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21213496 and 21213505.

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 3 ways as a sum of consecutive naturals, for example, 3032 + ... + 7184.

It is an arithmetic number, because the mean of its divisors is an integer number (3096807).

Almost surely, 2^21213524 is an apocalyptic number.

It is an amenable number.

21213524 is a deficient number, since it is larger than the sum of its proper divisors (15948160).

21213524 is a wasteful number, since it uses less digits than its factorization.

21213524 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5434 (or 5432 counting only the distinct ones).

The product of its digits is 480, while the sum is 20.

The square root of 21213524 is about 4605.8141517000. The cubic root of 21213524 is about 276.8243400528.

Adding to 21213524 its reverse (42531212), we get a palindrome (63744736).

The spelling of 21213524 in words is "twenty-one million, two hundred thirteen thousand, five hundred twenty-four".