21518524 has 24 divisors (see below), whose sum is σ = 39892608. Its totient is φ = 10134960.

The previous prime is 21518521. The next prime is 21518531. The reversal of 21518524 is 42581512.

It is a junction number, because it is equal to n+sod(n) for n = 21518492 and 21518501.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21518521) 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 7 ways as a sum of consecutive naturals, for example, 4419 + ... + 7909.

It is an arithmetic number, because the mean of its divisors is an integer number (1662192).

Almost surely, 2^21518524 is an apocalyptic number.

It is an amenable number.

21518524 is a deficient number, since it is larger than the sum of its proper divisors (18374084).

21518524 is a wasteful number, since it uses less digits than its factorization.

21518524 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3585 (or 3583 counting only the distinct ones).

The product of its digits is 3200, while the sum is 28.

The square root of 21518524 is about 4638.8063119729. The cubic root of 21518524 is about 278.1447239137.

The spelling of 21518524 in words is "twenty-one million, five hundred eighteen thousand, five hundred twenty-four".