199821969394 has 4 divisors (see below), whose sum is σ = 299732954094. Its totient is φ = 99910984696.

The previous prime is 199821969317. The next prime is 199821969397. The reversal of 199821969394 is 493969128991.

It is a happy number.

199821969394 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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

It can be written as a sum of positive squares in only one way, i.e., 171019467025 + 28802502369 = 413545^2 + 169713^2 .

It is not an unprimeable number, because it can be changed into a prime (199821969397) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 49955492347 + ... + 49955492350.

Almost surely, 2^199821969394 is an apocalyptic number.

199821969394 is a deficient number, since it is larger than the sum of its proper divisors (99910984700).

199821969394 is an equidigital number, since it uses as much as digits as its factorization.

199821969394 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 99910984699.

The product of its digits is 68024448, while the sum is 70.

The spelling of 199821969394 in words is "one hundred ninety-nine billion, eight hundred twenty-one million, nine hundred sixty-nine thousand, three hundred ninety-four".