21028185 has 12 divisors (see below), whose sum is σ = 36448932. Its totient is φ = 11215008.

The previous prime is 21028181. The next prime is 21028211. The reversal of 21028185 is 58182012.

It can be written as a sum of positive squares in 2 ways, for example, as 7033104 + 13995081 = 2652^2 + 3741^2 .

It is not a de Polignac number, because 21028185 - 2² = 21028181 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21028181) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 233602 + ... + 233691.

It is an arithmetic number, because the mean of its divisors is an integer number (3037411).

Almost surely, 2^21028185 is an apocalyptic number.

It is an amenable number.

21028185 is a deficient number, since it is larger than the sum of its proper divisors (15420747).

21028185 is a wasteful number, since it uses less digits than its factorization.

21028185 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 467304 (or 467301 counting only the distinct ones).

The product of its (nonzero) digits is 1280, while the sum is 27.

The square root of 21028185 is about 4585.6498994145. The cubic root of 21028185 is about 276.0157914720.

The spelling of 21028185 in words is "twenty-one million, twenty-eight thousand, one hundred eighty-five".