21524340 has 96 divisors (see below), whose sum is σ = 64512000. Its totient is φ = 5346432.

The previous prime is 21524333. The next prime is 21524369. The reversal of 21524340 is 4342512.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 89941 + ... + 90179.

It is an arithmetic number, because the mean of its divisors is an integer number (672000).

Almost surely, 2^21524340 is an apocalyptic number.

21524340 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21524340, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32256000).

21524340 is an abundant number, since it is smaller than the sum of its proper divisors (42987660).

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

21524340 is a wasteful number, since it uses less digits than its factorization.

21524340 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 349 (or 347 counting only the distinct ones).

The product of its (nonzero) digits is 960, while the sum is 21.

The square root of 21524340 is about 4639.4331550309. The cubic root of 21524340 is about 278.1697805268.

Adding to 21524340 its reverse (4342512), we get a palindrome (25866852).

The spelling of 21524340 in words is "twenty-one million, five hundred twenty-four thousand, three hundred forty".