1991816278147 has 2 divisors, whose sum is σ = 1991816278148. Its totient is φ = 1991816278146.

The previous prime is 1991816278079. The next prime is 1991816278201. The reversal of 1991816278147 is 7418726181991.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 1991816278147 - 2³¹ = 1989668794499 is a prime.

It is not a weakly prime, because it can be changed into another prime (1991816278447) by changing a digit.

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, 995908139073 + 995908139074.

It is an arithmetic number, because the mean of its divisors is an integer number (995908139074).

Almost surely, 2^{1991816278147} is an apocalyptic number.

1991816278147 is a deficient number, since it is larger than the sum of its proper divisors (1).

1991816278147 is an equidigital number, since it uses as much as digits as its factorization.

1991816278147 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 12192768, while the sum is 64.

The spelling of 1991816278147 in words is "one trillion, nine hundred ninety-one billion, eight hundred sixteen million, two hundred seventy-eight thousand, one hundred forty-seven".