21315275 has 12 divisors (see below), whose sum is σ = 26931312. Its totient is φ = 16729440.

The previous prime is 21315271. The next prime is 21315289. The reversal of 21315275 is 57251312.

It is not a de Polignac number, because 21315275 - 2² = 21315271 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21315271) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 6719 + ... + 9368.

It is an arithmetic number, because the mean of its divisors is an integer number (2244276).

Almost surely, 2^21315275 is an apocalyptic number.

21315275 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21315275 is a deficient number, since it is larger than the sum of its proper divisors (5616037).

21315275 is a wasteful number, since it uses less digits than its factorization.

21315275 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16150 (or 16145 counting only the distinct ones).

The product of its digits is 2100, while the sum is 26.

The square root of 21315275 is about 4616.8468677226. The cubic root of 21315275 is about 277.2662317177.

Adding to 21315275 its reverse (57251312), we get a palindrome (78566587).

The spelling of 21315275 in words is "twenty-one million, three hundred fifteen thousand, two hundred seventy-five".