21185285 has 36 divisors (see below), whose sum is σ = 29795724. Its totient is φ = 14446080.

The previous prime is 21185261. The next prime is 21185287. The reversal of 21185285 is 58258112.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 8561476 + 12623809 = 2926^2 + 3553^2 .

It is not a de Polignac number, because 21185285 - 2⁶ = 21185221 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21185287) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 218357 + ... + 218453.

It is an arithmetic number, because the mean of its divisors is an integer number (827659).

Almost surely, 2^21185285 is an apocalyptic number.

It is an amenable number.

21185285 is a deficient number, since it is larger than the sum of its proper divisors (8610439).

21185285 is a wasteful number, since it uses less digits than its factorization.

21185285 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 162 (or 132 counting only the distinct ones).

The product of its digits is 6400, while the sum is 32.

The square root of 21185285 is about 4602.7475490190. The cubic root of 21185285 is about 276.7014512481.

The spelling of 21185285 in words is "twenty-one million, one hundred eighty-five thousand, two hundred eighty-five".