21438128 has 20 divisors (see below), whose sum is σ = 41611920. Its totient is φ = 10699584.

The previous prime is 21438103. The next prime is 21438187. The reversal of 21438128 is 82183412.

It is a self number, because there is not a number n which added to its sum of digits gives 21438128.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 12626 + ... + 14222.

It is an arithmetic number, because the mean of its divisors is an integer number (2080596).

Almost surely, 2^21438128 is an apocalyptic number.

It is an amenable number.

21438128 is a deficient number, since it is larger than the sum of its proper divisors (20173792).

21438128 is a wasteful number, since it uses less digits than its factorization.

21438128 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2444 (or 2438 counting only the distinct ones).

The product of its digits is 3072, while the sum is 29.

The square root of 21438128 is about 4630.1326114918. The cubic root of 21438128 is about 277.7978966880.

The spelling of 21438128 in words is "twenty-one million, four hundred thirty-eight thousand, one hundred twenty-eight".