21885440 has 80 divisors (see below), whose sum is σ = 53621568. Its totient is φ = 8564736.

The previous prime is 21885439. The next prime is 21885491. The reversal of 21885440 is 4458812.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (80).

It is a Harshad number since it is a multiple of its sum of digits (32).

It is a junction number, because it is equal to n+sod(n) for n = 21885397 and 21885406.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 212429 + ... + 212531.

Almost surely, 2^21885440 is an apocalyptic number.

21885440 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 21885440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26810784).

21885440 is an abundant number, since it is smaller than the sum of its proper divisors (31736128).

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

21885440 is an equidigital number, since it uses as much as digits as its factorization.

21885440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 209 (or 193 counting only the distinct ones).

The product of its (nonzero) digits is 10240, while the sum is 32.

The square root of 21885440 is about 4678.1876832808. The cubic root of 21885440 is about 279.7167203016.

It can be divided in two parts, 218 and 85440, that added together give a palindrome (85658).

The spelling of 21885440 in words is "twenty-one million, eight hundred eighty-five thousand, four hundred forty".