21704128 has 14 divisors (see below), whose sum is σ = 43069256. Its totient is φ = 10852032.

The previous prime is 21704117. The next prime is 21704131. The reversal of 21704128 is 82140712.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 169500 + ... + 169627.

Almost surely, 2^21704128 is an apocalyptic number.

It is an amenable number.

21704128 is a deficient number, since it is larger than the sum of its proper divisors (21365128).

21704128 is an equidigital number, since it uses as much as digits as its factorization.

21704128 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 339139 (or 339129 counting only the distinct ones).

The product of its (nonzero) digits is 896, while the sum is 25.

The square root of 21704128 is about 4658.7689361032. The cubic root of 21704128 is about 278.9421307417.

The spelling of 21704128 in words is "twenty-one million, seven hundred four thousand, one hundred twenty-eight".