21546240 has 144 divisors (see below), whose sum is σ = 71425536. Its totient is φ = 5529600.

The previous prime is 21546233. The next prime is 21546241. The reversal of 21546240 is 4264512.

It is a hoax number, since the sum of its digits (24) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a self number, because there is not a number n which added to its sum of digits gives 21546240.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21546241) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 118950 + ... + 119130.

Almost surely, 2^21546240 is an apocalyptic number.

21546240 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 21546240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35712768).

21546240 is an abundant number, since it is smaller than the sum of its proper divisors (49879296).

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

21546240 is a wasteful number, since it uses less digits than its factorization.

21546240 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 236 (or 222 counting only the distinct ones).

The product of its (nonzero) digits is 1920, while the sum is 24.

The square root of 21546240 is about 4641.7927571144. The cubic root of 21546240 is about 278.2640900895.

The spelling of 21546240 in words is "twenty-one million, five hundred forty-six thousand, two hundred forty".