21312524 has 12 divisors (see below), whose sum is σ = 37436448. Its totient is φ = 10616400.

The previous prime is 21312523. The next prime is 21312539. The reversal of 21312524 is 42521312.

It is a junction number, because it is equal to n+sod(n) for n = 21312496 and 21312505.

It is not an unprimeable number, because it can be changed into a prime (21312523) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8747 + ... + 10914.

It is an arithmetic number, because the mean of its divisors is an integer number (3119704).

Almost surely, 2^21312524 is an apocalyptic number.

It is an amenable number.

21312524 is a deficient number, since it is larger than the sum of its proper divisors (16123924).

21312524 is a wasteful number, since it uses less digits than its factorization.

21312524 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19936 (or 19934 counting only the distinct ones).

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

The square root of 21312524 is about 4616.5489274998. The cubic root of 21312524 is about 277.2543029918.

Adding to 21312524 its reverse (42521312), we get a palindrome (63833836).

The spelling of 21312524 in words is "twenty-one million, three hundred twelve thousand, five hundred twenty-four".