21593 has 8 divisors (see below), whose sum is σ = 25536. Its totient is φ = 18000.

The previous prime is 21589. The next prime is 21599. The reversal of 21593 is 39512.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21593 - 2² = 21589 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21599) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 68 + ... + 218.

It is an arithmetic number, because the mean of its divisors is an integer number (3192).

2²¹⁵⁹³ is an apocalyptic number.

It is an amenable number.

21593 is a deficient number, since it is larger than the sum of its proper divisors (3943).

21593 is a wasteful number, since it uses less digits than its factorization.

21593 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 175.

The product of its digits is 270, while the sum is 20.

The square root of 21593 is about 146.9455681537. The cubic root of 21593 is about 27.8465242394.

The spelling of 21593 in words is "twenty-one thousand, five hundred ninety-three".