21703 has 4 divisors (see below), whose sum is σ = 23688. Its totient is φ = 19720.

The previous prime is 21701. The next prime is 21713. The reversal of 21703 is 30712.

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 21703 - 2¹ = 21701 is a prime.

It is a Duffinian number.

21703 is a lucky number.

It is a plaindrome in base 15.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21701) 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, 976 + ... + 997.

It is an arithmetic number, because the mean of its divisors is an integer number (5922).

2²¹⁷⁰³ is an apocalyptic number.

21703 is a deficient number, since it is larger than the sum of its proper divisors (1985).

21703 is a wasteful number, since it uses less digits than its factorization.

21703 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1984.

The product of its (nonzero) digits is 42, while the sum is 13.

The square root of 21703 is about 147.3193809382. The cubic root of 21703 is about 27.8937298294.

Subtracting 21703 from its reverse (30712), we obtain a palindrome (9009).

The spelling of 21703 in words is "twenty-one thousand, seven hundred three", and thus it is an iban number.