21708560 has 20 divisors (see below), whose sum is σ = 50472588. Its totient is φ = 8683392.

The previous prime is 21708553. The next prime is 21708563. The reversal of 21708560 is 6580712.

It can be written as a sum of positive squares in 2 ways, for example, as 10445824 + 11262736 = 3232^2 + 3356^2 .

It is a tau number, because it is divible by the number of its divisors (20).

It is not an unprimeable number, because it can be changed into a prime (21708563) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 135599 + ... + 135758.

Almost surely, 2^21708560 is an apocalyptic number.

21708560 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21708560 is an abundant number, since it is smaller than the sum of its proper divisors (28764028).

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

21708560 is a wasteful number, since it uses less digits than its factorization.

21708560 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 271370 (or 271364 counting only the distinct ones).

The product of its (nonzero) digits is 3360, while the sum is 29.

The square root of 21708560 is about 4659.2445739626. The cubic root of 21708560 is about 278.9611161837.

The spelling of 21708560 in words is "twenty-one million, seven hundred eight thousand, five hundred sixty".