21688275 has 48 divisors (see below), whose sum is σ = 41465600. Its totient is φ = 9797760.

The previous prime is 21688237. The next prime is 21688279. The reversal of 21688275 is 57288612.

It is not a de Polignac number, because 21688275 - 2⁹ = 21687763 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21688279) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 57036 + ... + 57414.

Almost surely, 2^21688275 is an apocalyptic number.

21688275 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21688275 is a deficient number, since it is larger than the sum of its proper divisors (19777325).

21688275 is a wasteful number, since it uses less digits than its factorization.

21688275 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 508 (or 503 counting only the distinct ones).

The product of its digits is 53760, while the sum is 39.

The square root of 21688275 is about 4657.0672101656. The cubic root of 21688275 is about 278.8741997828.

The spelling of 21688275 in words is "twenty-one million, six hundred eighty-eight thousand, two hundred seventy-five".