21927 has 4 divisors (see below), whose sum is σ = 29240. Its totient is φ = 14616.

The previous prime is 21911. The next prime is 21929. The reversal of 21927 is 72912.

It is a happy number.

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

It is not a de Polignac number, because 21927 - 2⁴ = 21911 is a prime.

It is a D-number.

It is a Duffinian number.

21927 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21929) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3652 + ... + 3657.

It is an arithmetic number, because the mean of its divisors is an integer number (7310).

2²¹⁹²⁷ is an apocalyptic number.

21927 is a deficient number, since it is larger than the sum of its proper divisors (7313).

21927 is an equidigital number, since it uses as much as digits as its factorization.

21927 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7312.

The product of its digits is 252, while the sum is 21.

The square root of 21927 is about 148.0776823157. The cubic root of 21927 is about 27.9893667107.

The spelling of 21927 in words is "twenty-one thousand, nine hundred twenty-seven".