19999643 has 8 divisors (see below), whose sum is σ = 20675760. Its totient is φ = 19334880.

The previous prime is 19999631. The next prime is 19999663. The reversal of 19999643 is 34699991.

It is a happy number.

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 19999643 - 2⁸ = 19999387 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 19999591 and 19999600.

It is not an unprimeable number, because it can be changed into a prime (19999663) 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, 821 + ... + 6377.

It is an arithmetic number, because the mean of its divisors is an integer number (2584470).

Almost surely, 2^19999643 is an apocalyptic number.

19999643 is a deficient number, since it is larger than the sum of its proper divisors (676117).

19999643 is an equidigital number, since it uses as much as digits as its factorization.

19999643 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5677.

The product of its digits is 472392, while the sum is 50.

The square root of 19999643 is about 4472.0960410081. The cubic root of 19999643 is about 271.4401465714.

The spelling of 19999643 in words is "nineteen million, nine hundred ninety-nine thousand, six hundred forty-three".