199643317421 has 4 divisors (see below), whose sum is σ = 204286185312. Its totient is φ = 195000449532.

The previous prime is 199643317417. The next prime is 199643317429. The reversal of 199643317421 is 124713346991.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 124713346991 = 41 ⋅3041788951.

It is a cyclic number.

It is not a de Polignac number, because 199643317421 - 2² = 199643317417 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 199643317421.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (199643317429) 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, 2321433881 + ... + 2321433966.

It is an arithmetic number, because the mean of its divisors is an integer number (51071546328).

Almost surely, 2^199643317421 is an apocalyptic number.

It is an amenable number.

199643317421 is a deficient number, since it is larger than the sum of its proper divisors (4642867891).

199643317421 is an equidigital number, since it uses as much as digits as its factorization.

199643317421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4642867890.

The product of its digits is 979776, while the sum is 50.

The spelling of 199643317421 in words is "one hundred ninety-nine billion, six hundred forty-three million, three hundred seventeen thousand, four hundred twenty-one".