11991800438 has 4 divisors (see below), whose sum is σ = 17987700660. Its totient is φ = 5995900218.

The previous prime is 11991800423. The next prime is 11991800449. The reversal of 11991800438 is 83400819911.

11991800438 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 is a congruent number.

It is an unprimeable number.

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 as a sum of consecutive naturals, namely, 2997950108 + ... + 2997950111.

It is an arithmetic number, because the mean of its divisors is an integer number (4496925165).

Almost surely, 2^11991800438 is an apocalyptic number.

11991800438 is a deficient number, since it is larger than the sum of its proper divisors (5995900222).

11991800438 is an equidigital number, since it uses as much as digits as its factorization.

11991800438 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5995900221.

The product of its (nonzero) digits is 62208, while the sum is 44.

The spelling of 11991800438 in words is "eleven billion, nine hundred ninety-one million, eight hundred thousand, four hundred thirty-eight".