21128236 has 12 divisors (see below), whose sum is σ = 38167360. Its totient is φ = 10223280.

The previous prime is 21128213. The next prime is 21128257. The reversal of 21128236 is 63282112.

It is a self number, because there is not a number n which added to its sum of digits gives 21128236.

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, 85071 + ... + 85318.

Almost surely, 2^21128236 is an apocalyptic number.

It is an amenable number.

21128236 is a deficient number, since it is larger than the sum of its proper divisors (17039124).

21128236 is a wasteful number, since it uses less digits than its factorization.

21128236 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 170424 (or 170422 counting only the distinct ones).

The product of its digits is 1152, while the sum is 25.

The square root of 21128236 is about 4596.5460946237. The cubic root of 21128236 is about 276.4528552416.

The spelling of 21128236 in words is "twenty-one million, one hundred twenty-eight thousand, two hundred thirty-six".