21319 has 2 divisors, whose sum is σ = 21320. Its totient is φ = 21318.

The previous prime is 21317. The next prime is 21323. The reversal of 21319 is 91312.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21319 - 2¹ = 21317 is a prime.

It is a super-2 number, since 2×21319² = 908999522, which contains 22 as substring.

Together with 21317, it forms a pair of twin primes.

It is a plaindrome in base 14.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21313) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10659 + 10660.

It is an arithmetic number, because the mean of its divisors is an integer number (10660).

2²¹³¹⁹ is an apocalyptic number.

21319 is a deficient number, since it is larger than the sum of its proper divisors (1).

21319 is an equidigital number, since it uses as much as digits as its factorization.

21319 is an evil number, because the sum of its binary digits is even.

The product of its digits is 54, while the sum is 16.

The square root of 21319 is about 146.0102736111. The cubic root of 21319 is about 27.7282382210.

It can be divided in two parts, 213 and 19, that added together give a palindrome (232).

The spelling of 21319 in words is "twenty-one thousand, three hundred nineteen".