21727 has 2 divisors, whose sum is σ = 21728. Its totient is φ = 21726.

The previous prime is 21713. The next prime is 21737. The reversal of 21727 is 72712.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21727 - 2⁷ = 21599 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21737) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10863 + 10864.

It is an arithmetic number, because the mean of its divisors is an integer number (10864).

2²¹⁷²⁷ is an apocalyptic number.

21727 is a deficient number, since it is larger than the sum of its proper divisors (1).

21727 is an equidigital number, since it uses as much as digits as its factorization.

21727 is an evil number, because the sum of its binary digits is even.

The product of its digits is 196, while the sum is 19.

The square root of 21727 is about 147.4008141090. The cubic root of 21727 is about 27.9040080229.

The spelling of 21727 in words is "twenty-one thousand, seven hundred twenty-seven", and thus it is an iban number.