21424524 has 48 divisors (see below), whose sum is σ = 55109376. Its totient is φ = 6424000.

The previous prime is 21424511. The next prime is 21424547. The reversal of 21424524 is 42542412.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 21424494 and 21424503.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 12529 + ... + 14135.

It is an arithmetic number, because the mean of its divisors is an integer number (1148112).

Almost surely, 2^21424524 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 21424524, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27554688).

21424524 is an abundant number, since it is smaller than the sum of its proper divisors (33684852).

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

21424524 is a wasteful number, since it uses less digits than its factorization.

21424524 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1726 (or 1724 counting only the distinct ones).

The product of its digits is 2560, while the sum is 24.

The square root of 21424524 is about 4628.6633059664. The cubic root of 21424524 is about 277.7391234865.

Adding to 21424524 its reverse (42542412), we get a palindrome (63966936).

It can be divided in two parts, 2142 and 4524, that added together give a palindrome (6666).

The spelling of 21424524 in words is "twenty-one million, four hundred twenty-four thousand, five hundred twenty-four".