21406428 has 36 divisors (see below), whose sum is σ = 55434288. Its totient is φ = 6960960.

The previous prime is 21406397. The next prime is 21406457. The reversal of 21406428 is 82460412.

21406428 is a `hidden beast` number, since 2 + 14 + 0 + 642 + 8 = 666.

It is a tau number, because it is divible by the number of its divisors (36).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 5776 + ... + 8727.

Almost surely, 2^21406428 is an apocalyptic number.

It is an amenable number.

21406428 is an abundant number, since it is smaller than the sum of its proper divisors (34027860).

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

21406428 is a wasteful number, since it uses less digits than its factorization.

21406428 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14554 (or 14549 counting only the distinct ones).

The product of its (nonzero) digits is 3072, while the sum is 27.

The square root of 21406428 is about 4626.7081170093. The cubic root of 21406428 is about 277.6609049788.

The spelling of 21406428 in words is "twenty-one million, four hundred six thousand, four hundred twenty-eight".