21885240 has 64 divisors (see below), whose sum is σ = 70711200. Its totient is φ = 5386752.

The previous prime is 21885229. The next prime is 21885257. The reversal of 21885240 is 4258812.

It is a hoax number, since the sum of its digits (30) 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 (30).

It is a junction number, because it is equal to n+sod(n) for n = 21885198 and 21885207.

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 15 ways as a sum of consecutive naturals, for example, 5455 + ... + 8574.

Almost surely, 2^21885240 is an apocalyptic number.

21885240 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21885240 is an abundant number, since it is smaller than the sum of its proper divisors (48825960).

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

21885240 is a wasteful number, since it uses less digits than its factorization.

21885240 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14056 (or 14052 counting only the distinct ones).

The product of its (nonzero) digits is 5120, while the sum is 30.

The square root of 21885240 is about 4678.1663074329. The cubic root of 21885240 is about 279.7158682356.

It can be divided in two parts, 218 and 85240, that added together give a palindrome (85458).

The spelling of 21885240 in words is "twenty-one million, eight hundred eighty-five thousand, two hundred forty".