21406328 has 16 divisors (see below), whose sum is σ = 40371480. Its totient is φ = 10640608.

The previous prime is 21406279. The next prime is 21406339. The reversal of 21406328 is 82360412.

It is a junction number, because it is equal to n+sod(n) for n = 21406297 and 21406306.

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 in 3 ways as a sum of consecutive naturals, for example, 6350 + ... + 9117.

Almost surely, 2^21406328 is an apocalyptic number.

It is an amenable number.

21406328 is a deficient number, since it is larger than the sum of its proper divisors (18965152).

21406328 is a wasteful number, since it uses less digits than its factorization.

21406328 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15646 (or 15642 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 26.

The square root of 21406328 is about 4626.6973101771. The cubic root of 21406328 is about 277.6604726144.

The spelling of 21406328 in words is "twenty-one million, four hundred six thousand, three hundred twenty-eight".