19643 has 4 divisors (see below), whose sum is σ = 21168. Its totient is φ = 18120.

The previous prime is 19609. The next prime is 19661. The reversal of 19643 is 34691.

19643 is nontrivially palindromic in base 12.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 34691 = 113 ⋅307.

It is a cyclic number.

It is not a de Polignac number, because 19643 - 2⁸ = 19387 is a prime.

It is a Duffinian number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 19643.

It is not an unprimeable number, because it can be changed into a prime (19603) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 743 + ... + 768.

It is an arithmetic number, because the mean of its divisors is an integer number (5292).

2¹⁹⁶⁴³ is an apocalyptic number.

19643 is a gapful number since it is divisible by the number (13) formed by its first and last digit.

19643 is a deficient number, since it is larger than the sum of its proper divisors (1525).

19643 is a wasteful number, since it uses less digits than its factorization.

19643 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1524.

The product of its digits is 648, while the sum is 23.

The square root of 19643 is about 140.1534872916. The cubic root of 19643 is about 26.9816977015.

The spelling of 19643 in words is "nineteen thousand, six hundred forty-three".