21864480 has 192 divisors, whose sum is σ = 77728896. Its totient is φ = 5120000.

The previous prime is 21864457. The next prime is 21864509. The reversal of 21864480 is 8446812.

It is a Harshad number since it is a multiple of its sum of digits (33).

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 216430 + ... + 216530.

It is an arithmetic number, because the mean of its divisors is an integer number (404838).

Almost surely, 2^21864480 is an apocalyptic number.

21864480 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 21864480, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38864448).

21864480 is an abundant number, since it is smaller than the sum of its proper divisors (55864416).

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

21864480 is a wasteful number, since it uses less digits than its factorization.

21864480 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 171 (or 163 counting only the distinct ones).

The product of its (nonzero) digits is 12288, while the sum is 33.

The square root of 21864480 is about 4675.9469629156. The cubic root of 21864480 is about 279.6273955404.

It can be divided in two parts, 2186 and 4480, that added together give a palindrome (6666).

The spelling of 21864480 in words is "twenty-one million, eight hundred sixty-four thousand, four hundred eighty".