16399 has 6 divisors (see below), whose sum is σ = 17696. Its totient is φ = 15180.

The previous prime is 16381. The next prime is 16411. The reversal of 16399 is 99361.

It is a happy number.

It is not a de Polignac number, because 16399 - 2⁹ = 15887 is a prime.

It is an Ulam number.

It is a Duffinian number.

Its product of digits (1458) is a multiple of the sum of its prime divisors (54).

It is a plaindrome in base 11.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16319) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 514 + ... + 544.

2¹⁶³⁹⁹ is an apocalyptic number.

16399 is a deficient number, since it is larger than the sum of its proper divisors (1297).

16399 is an equidigital number, since it uses as much as digits as its factorization.

16399 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 77 (or 54 counting only the distinct ones).

The product of its digits is 1458, while the sum is 28.

The square root of 16399 is about 128.0585803451. The cubic root of 16399 is about 25.4061654490.

Subtracting from 16399 its product of digits (1458), we obtain a palindrome (14941).

It can be divided in two parts, 163 and 99, that added together give a palindrome (262).

The spelling of 16399 in words is "sixteen thousand, three hundred ninety-nine".