21704856 has 16 divisors (see below), whose sum is σ = 54262200. Its totient is φ = 7234944.

The previous prime is 21704833. The next prime is 21704857. The reversal of 21704856 is 65840712.

It is a super-2 number, since 2×21704856² = 942201547961472, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21704857) 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, 452161 + ... + 452208.

Almost surely, 2^21704856 is an apocalyptic number.

It is an amenable number.

21704856 is an abundant number, since it is smaller than the sum of its proper divisors (32557344).

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

21704856 is a wasteful number, since it uses less digits than its factorization.

21704856 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 904378 (or 904374 counting only the distinct ones).

The product of its (nonzero) digits is 13440, while the sum is 33.

The square root of 21704856 is about 4658.8470676767. The cubic root of 21704856 is about 278.9452494665.

The spelling of 21704856 in words is "twenty-one million, seven hundred four thousand, eight hundred fifty-six".