21347 has 2 divisors, whose sum is σ = 21348. Its totient is φ = 21346.

The previous prime is 21341. The next prime is 21377. The reversal of 21347 is 74312.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21347 - 2⁶ = 21283 is a prime.

It is a Chen prime.

It is an Ulam number.

It is a nialpdrome in base 13.

It is not a weakly prime, because it can be changed into another prime (21341) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10673 + 10674.

It is an arithmetic number, because the mean of its divisors is an integer number (10674).

2²¹³⁴⁷ is an apocalyptic number.

21347 is a deficient number, since it is larger than the sum of its proper divisors (1).

21347 is an equidigital number, since it uses as much as digits as its factorization.

21347 is an evil number, because the sum of its binary digits is even.

The product of its digits is 168, while the sum is 17.

The square root of 21347 is about 146.1061258127. The cubic root of 21347 is about 27.7403721707.

Adding to 21347 its reverse (74312), we get a palindrome (95659).

It can be divided in two parts, 213 and 47, that multiplied together give a triangular number (10011 = T₁₄₁).

The spelling of 21347 in words is "twenty-one thousand, three hundred forty-seven", and thus it is an iban number.