21312275 has 12 divisors (see below), whose sum is σ = 26877000. Its totient is φ = 16759680.

The previous prime is 21312257. The next prime is 21312289. The reversal of 21312275 is 57221312.

It is a happy number.

It is not a de Polignac number, because 21312275 - 2⁸ = 21312019 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21312275.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 5750 + ... + 8699.

It is an arithmetic number, because the mean of its divisors is an integer number (2239750).

Almost surely, 2^21312275 is an apocalyptic number.

21312275 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21312275 is a deficient number, since it is larger than the sum of its proper divisors (5564725).

21312275 is a wasteful number, since it uses less digits than its factorization.

21312275 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14518 (or 14513 counting only the distinct ones).

The product of its digits is 840, while the sum is 23.

The square root of 21312275 is about 4616.5219592243. The cubic root of 21312275 is about 277.2532232419.

Adding to 21312275 its reverse (57221312), we get a palindrome (78533587).

The spelling of 21312275 in words is "twenty-one million, three hundred twelve thousand, two hundred seventy-five".