12001991209978 has 48 divisors (see below), whose sum is σ = 23167866950208. Its totient is φ = 4610239872000.

The previous prime is 12001991209961. The next prime is 12001991209987. The reversal of 12001991209978 is 87990219910021.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 78328903 + ... + 78481978.

It is an arithmetic number, because the mean of its divisors is an integer number (482663894796).

Almost surely, 2^{12001991209978} is an apocalyptic number.

12001991209978 is a deficient number, since it is larger than the sum of its proper divisors (11165875740230).

12001991209978 is a wasteful number, since it uses less digits than its factorization.

12001991209978 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 156810979 (or 156810972 counting only the distinct ones).

The product of its (nonzero) digits is 1469664, while the sum is 58.

The spelling of 12001991209978 in words is "twelve trillion, one billion, nine hundred ninety-one million, two hundred nine thousand, nine hundred seventy-eight".