13999 has 2 divisors, whose sum is σ = 14000. Its totient is φ = 13998.

The previous prime is 13997. The next prime is 14009. The reversal of 13999 is 99931.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 13999 - 2¹ = 13997 is a prime.

Together with 13997, it forms a pair of twin primes.

13999 is a modest number, since divided by 999 gives 13 as remainder.

It is a plaindrome in base 10 and base 16.

It is a self number, because there is not a number n which added to its sum of digits gives 13999.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (13997) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 6999 + 7000.

It is an arithmetic number, because the mean of its divisors is an integer number (7000).

2¹³⁹⁹⁹ is an apocalyptic number.

13999 is a deficient number, since it is larger than the sum of its proper divisors (1).

13999 is an equidigital number, since it uses as much as digits as its factorization.

13999 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2187, while the sum is 31.

The square root of 13999 is about 118.3173698153. The cubic root of 13999 is about 24.1008487847.

The spelling of 13999 in words is "thirteen thousand, nine hundred ninety-nine".