21403128 has 16 divisors (see below), whose sum is σ = 53507880. Its totient is φ = 7134368.

The previous prime is 21403117. The next prime is 21403159. The reversal of 21403128 is 82130412.

It is a congruent number.

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 445875 + ... + 445922.

Almost surely, 2^21403128 is an apocalyptic number.

It is an amenable number.

21403128 is an abundant number, since it is smaller than the sum of its proper divisors (32104752).

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

21403128 is a wasteful number, since it uses less digits than its factorization.

21403128 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 891806 (or 891802 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 21.

The square root of 21403128 is about 4626.3514782169. The cubic root of 21403128 is about 277.6466362418.

The spelling of 21403128 in words is "twenty-one million, four hundred three thousand, one hundred twenty-eight".