21306275 has 12 divisors (see below), whose sum is σ = 26983392. Its totient is φ = 16681440.

The previous prime is 21306247. The next prime is 21306281. The reversal of 21306275 is 57260312.

It is a de Polignac number, because none of the positive numbers 2^k-21306275 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 7892 + ... + 10241.

It is an arithmetic number, because the mean of its divisors is an integer number (2248616).

Almost surely, 2^21306275 is an apocalyptic number.

21306275 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21306275 is a deficient number, since it is larger than the sum of its proper divisors (5677117).

21306275 is a wasteful number, since it uses less digits than its factorization.

21306275 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18190 (or 18185 counting only the distinct ones).

The product of its (nonzero) digits is 2520, while the sum is 26.

The square root of 21306275 is about 4615.8720736173. The cubic root of 21306275 is about 277.2272026274.

Adding to 21306275 its reverse (57260312), we get a palindrome (78566587).

The spelling of 21306275 in words is "twenty-one million, three hundred six thousand, two hundred seventy-five".