21705344 has 32 divisors (see below), whose sum is σ = 43566240. Its totient is φ = 10771200.

The previous prime is 21705337. The next prime is 21705367. The reversal of 21705344 is 44350712.

It is a tau number, because it is divible by the number of its divisors (32).

It is a super-2 number, since 2×21705344² = 942243916316672, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 18767 + ... + 19889.

It is an arithmetic number, because the mean of its divisors is an integer number (1361445).

Almost surely, 2^21705344 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21705344, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (21783120).

21705344 is an abundant number, since it is smaller than the sum of its proper divisors (21860896).

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

21705344 is a wasteful number, since it uses less digits than its factorization.

21705344 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1288 (or 1276 counting only the distinct ones).

The product of its (nonzero) digits is 3360, while the sum is 26.

The square root of 21705344 is about 4658.8994408551. The cubic root of 21705344 is about 278.9473400011.

The spelling of 21705344 in words is "twenty-one million, seven hundred five thousand, three hundred forty-four".