21834240 has 80 divisors (see below), whose sum is σ = 69825888. Its totient is φ = 5820416.

The previous prime is 21834233. The next prime is 21834269. The reversal of 21834240 is 4243812.

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 (24).

It is a self number, because there is not a number n which added to its sum of digits gives 21834240.

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, 6259 + ... + 9101.

Almost surely, 2^21834240 is an apocalyptic number.

21834240 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 21834240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34912944).

21834240 is an abundant number, since it is smaller than the sum of its proper divisors (47991648).

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

21834240 is an equidigital number, since it uses as much as digits as its factorization.

21834240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2869 (or 2853 counting only the distinct ones).

The product of its (nonzero) digits is 1536, while the sum is 24.

The square root of 21834240 is about 4672.7122744719. The cubic root of 21834240 is about 279.4984217618.

The spelling of 21834240 in words is "twenty-one million, eight hundred thirty-four thousand, two hundred forty".