19917943 has 4 divisors (see below), whose sum is σ = 20104200. Its totient is φ = 19731688.

The previous prime is 19917941. The next prime is 19917949. The reversal of 19917943 is 34971991.

It is a happy number.

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 19917943 - 2¹ = 19917941 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 19917943.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19917941) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 92968 + ... + 93181.

It is an arithmetic number, because the mean of its divisors is an integer number (5026050).

Almost surely, 2^19917943 is an apocalyptic number.

19917943 is a deficient number, since it is larger than the sum of its proper divisors (186257).

19917943 is a wasteful number, since it uses less digits than its factorization.

19917943 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 186256.

The product of its digits is 61236, while the sum is 43.

The square root of 19917943 is about 4462.9522739998. The cubic root of 19917943 is about 271.0700245238.

The spelling of 19917943 in words is "nineteen million, nine hundred seventeen thousand, nine hundred forty-three".