21255271 has 4 divisors (see below), whose sum is σ = 21298032. Its totient is φ = 21212512.

The previous prime is 21255263. The next prime is 21255277. The reversal of 21255271 is 17255212.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21255271 - 2³ = 21255263 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21255277) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 20626 + ... + 21631.

It is an arithmetic number, because the mean of its divisors is an integer number (5324508).

Almost surely, 2^21255271 is an apocalyptic number.

21255271 is a deficient number, since it is larger than the sum of its proper divisors (42761).

21255271 is an equidigital number, since it uses as much as digits as its factorization.

21255271 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 42760.

The product of its digits is 1400, while the sum is 25.

The square root of 21255271 is about 4610.3439134190. The cubic root of 21255271 is about 277.0058125434.

It can be divided in two parts, 2125 and 5271, that added together give a square (7396 = 86²).

The spelling of 21255271 in words is "twenty-one million, two hundred fifty-five thousand, two hundred seventy-one".