21704560 has 40 divisors (see below), whose sum is σ = 51425280. Its totient is φ = 8516352.

The previous prime is 21704549. The next prime is 21704567. The reversal of 21704560 is 6540712.

It is a tau number, because it is divible by the number of its divisors (40).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21704567) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 1681 + ... + 6799.

It is an arithmetic number, because the mean of its divisors is an integer number (1285632).

Almost surely, 2^21704560 is an apocalyptic number.

21704560 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 21704560, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25712640).

21704560 is an abundant number, since it is smaller than the sum of its proper divisors (29720720).

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

21704560 is a wasteful number, since it uses less digits than its factorization.

21704560 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5185 (or 5179 counting only the distinct ones).

The product of its (nonzero) digits is 1680, while the sum is 25.

The square root of 21704560 is about 4658.8153000521. The cubic root of 21704560 is about 278.9439814220.

The spelling of 21704560 in words is "twenty-one million, seven hundred four thousand, five hundred sixty".