21583 has 4 divisors (see below), whose sum is σ = 21888. Its totient is φ = 21280.

The previous prime is 21577. The next prime is 21587. The reversal of 21583 is 38512.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21583 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21583.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21587) 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, 18 + ... + 208.

It is an arithmetic number, because the mean of its divisors is an integer number (5472).

2²¹⁵⁸³ is an apocalyptic number.

21583 is a deficient number, since it is larger than the sum of its proper divisors (305).

21583 is a wasteful number, since it uses less digits than its factorization.

21583 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 304.

The product of its digits is 240, while the sum is 19.

The square root of 21583 is about 146.9115380084. The cubic root of 21583 is about 27.8422248794.

The spelling of 21583 in words is "twenty-one thousand, five hundred eighty-three".