21135185 has 4 divisors (see below), whose sum is σ = 25362228. Its totient is φ = 16908144.

The previous prime is 21135173. The next prime is 21135223. The reversal of 21135185 is 58153112.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 12159169 + 8976016 = 3487^2 + 2996^2 .

It is a cyclic number.

It is not a de Polignac number, because 21135185 - 2⁸ = 21134929 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2113514 + ... + 2113523.

It is an arithmetic number, because the mean of its divisors is an integer number (6340557).

Almost surely, 2^21135185 is an apocalyptic number.

It is an amenable number.

21135185 is a deficient number, since it is larger than the sum of its proper divisors (4227043).

21135185 is an equidigital number, since it uses as much as digits as its factorization.

21135185 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4227042.

The product of its digits is 1200, while the sum is 26.

The square root of 21135185 is about 4597.3019261302. The cubic root of 21135185 is about 276.4831600324.

Adding to 21135185 its reverse (58153112), we get a palindrome (79288297).

The spelling of 21135185 in words is "twenty-one million, one hundred thirty-five thousand, one hundred eighty-five".