21321275 has 6 divisors (see below), whose sum is σ = 26438412. Its totient is φ = 17057000.

The previous prime is 21321263. The next prime is 21321277. The reversal of 21321275 is 57212312.

It is a happy number.

It is not a de Polignac number, because 21321275 - 2⁸ = 21321019 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21321275.

It is not an unprimeable number, because it can be changed into a prime (21321277) by changing a digit.

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 5 ways as a sum of consecutive naturals, for example, 426401 + ... + 426450.

It is an arithmetic number, because the mean of its divisors is an integer number (4406402).

Almost surely, 2^21321275 is an apocalyptic number.

21321275 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21321275 is a deficient number, since it is larger than the sum of its proper divisors (5117137).

21321275 is an equidigital number, since it uses as much as digits as its factorization.

21321275 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 852861 (or 852856 counting only the distinct ones).

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

The square root of 21321275 is about 4617.4966161330. The cubic root of 21321275 is about 277.2922450082.

Adding to 21321275 its reverse (57212312), we get a palindrome (78533587).

The spelling of 21321275 in words is "twenty-one million, three hundred twenty-one thousand, two hundred seventy-five".