19993 has 2 divisors, whose sum is σ = 19994. Its totient is φ = 19992.

The previous prime is 19991. The next prime is 19997. The reversal of 19993 is 39991.

19993 is an esthetic number in base 6, because in such base its adjacent digits differ by 1.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17689 + 2304 = 133^2 + 48^2 .

It is a cyclic number.

It is not a de Polignac number, because 19993 - 2¹ = 19991 is a prime.

Together with 19991, it forms a pair of twin primes.

19993 is a lucky number.

It is a zygodrome in base 5.

It is not a weakly prime, because it can be changed into another prime (19991) 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 as a sum of consecutive naturals, namely, 9996 + 9997.

It is an arithmetic number, because the mean of its divisors is an integer number (9997).

2¹⁹⁹⁹³ is an apocalyptic number.

It is an amenable number.

19993 is a deficient number, since it is larger than the sum of its proper divisors (1).

19993 is an equidigital number, since it uses as much as digits as its factorization.

19993 is an odious number, because the sum of its binary digits is odd.

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

The square root of 19993 is about 141.3966053341. The cubic root of 19993 is about 27.1410089759.

It can be divided in two parts, 1999 and 3, that added together give a palindrome (2002).

The spelling of 19993 in words is "nineteen thousand, nine hundred ninety-three".