21259 has 4 divisors (see below), whose sum is σ = 24304. Its totient is φ = 18216.

The previous prime is 21247. The next prime is 21269. The reversal of 21259 is 95212.

21259 = 57² + 58² + ... + 62².

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 21259 - 2⁵ = 21227 is a prime.

21259 is a modest number, since divided by 259 gives 21 as remainder.

It is not an unprimeable number, because it can be changed into a prime (21269) 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 3 ways as a sum of consecutive naturals, for example, 1512 + ... + 1525.

It is an arithmetic number, because the mean of its divisors is an integer number (6076).

2²¹²⁵⁹ is an apocalyptic number.

21259 is a deficient number, since it is larger than the sum of its proper divisors (3045).

21259 is an equidigital number, since it uses as much as digits as its factorization.

21259 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3044.

The product of its digits is 180, while the sum is 19.

The square root of 21259 is about 145.8046638486. The cubic root of 21259 is about 27.7022010789.

The spelling of 21259 in words is "twenty-one thousand, two hundred fifty-nine".