19998643 has 8 divisors (see below), whose sum is σ = 22900320. Its totient is φ = 17108160.

The previous prime is 19998637. The next prime is 19998653. The reversal of 19998643 is 34689991.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 19998643 - 2²¹ = 17901491 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (19998653) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1473 + ... + 6493.

It is an arithmetic number, because the mean of its divisors is an integer number (2862540).

Almost surely, 2^19998643 is an apocalyptic number.

19998643 is a deficient number, since it is larger than the sum of its proper divisors (2901677).

19998643 is an equidigital number, since it uses as much as digits as its factorization.

19998643 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5597.

The product of its digits is 419904, while the sum is 49.

The square root of 19998643 is about 4471.9842352137. The cubic root of 19998643 is about 271.4356224128.

The spelling of 19998643 in words is "nineteen million, nine hundred ninety-eight thousand, six hundred forty-three".