21125185 has 4 divisors (see below), whose sum is σ = 25350228. Its totient is φ = 16900144.

The previous prime is 21125183. The next prime is 21125219. The reversal of 21125185 is 58152112.

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 12173121 + 8952064 = 3489^2 + 2992^2 .

It is a cyclic number.

It is not a de Polignac number, because 21125185 - 2¹ = 21125183 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21125183) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2112514 + ... + 2112523.

It is an arithmetic number, because the mean of its divisors is an integer number (6337557).

Almost surely, 2^21125185 is an apocalyptic number.

It is an amenable number.

21125185 is a deficient number, since it is larger than the sum of its proper divisors (4225043).

21125185 is an equidigital number, since it uses as much as digits as its factorization.

21125185 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4225042.

The product of its digits is 800, while the sum is 25.

The square root of 21125185 is about 4596.2142030153. The cubic root of 21125185 is about 276.4395476428.

Adding to 21125185 its reverse (58152112), we get a palindrome (79277297).

The spelling of 21125185 in words is "twenty-one million, one hundred twenty-five thousand, one hundred eighty-five".