19999943 has 4 divisors (see below), whose sum is σ = 20540520. Its totient is φ = 19459368.

The previous prime is 19999927. The next prime is 19999963. The reversal of 19999943 is 34999991.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 19999943 - 2⁴ = 19999927 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19999963) 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, 270233 + ... + 270306.

It is an arithmetic number, because the mean of its divisors is an integer number (5135130).

Almost surely, 2^19999943 is an apocalyptic number.

19999943 is a deficient number, since it is larger than the sum of its proper divisors (540577).

19999943 is an equidigital number, since it uses as much as digits as its factorization.

19999943 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 540576.

The product of its digits is 708588, while the sum is 53.

The square root of 19999943 is about 4472.1295822013. The cubic root of 19999943 is about 271.4415037896.

The spelling of 19999943 in words is "nineteen million, nine hundred ninety-nine thousand, nine hundred forty-three".