21556271 has 6 divisors (see below), whose sum is σ = 23694216. Its totient is φ = 19596500.

The previous prime is 21556247. The next prime is 21556273. The reversal of 21556271 is 17265512.

It is not a de Polignac number, because 21556271 - 2¹⁸ = 21294127 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 (21556273) 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, 88955 + ... + 89196.

It is an arithmetic number, because the mean of its divisors is an integer number (3949036).

Almost surely, 2^21556271 is an apocalyptic number.

21556271 is a deficient number, since it is larger than the sum of its proper divisors (2137945).

21556271 is a wasteful number, since it uses less digits than its factorization.

21556271 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 178173 (or 178162 counting only the distinct ones).

The product of its digits is 4200, while the sum is 29.

The square root of 21556271 is about 4642.8731406318. The cubic root of 21556271 is about 278.3072659760.

The spelling of 21556271 in words is "twenty-one million, five hundred fifty-six thousand, two hundred seventy-one".