991211202012089 has 2 divisors, whose sum is σ = 991211202012090. Its totient is φ = 991211202012088.

The previous prime is 991211202012077. The next prime is 991211202012131. The reversal of 991211202012089 is 980210202112199.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 990177878936464 + 1033323075625 = 31467092^2 + 1016525^2 .

It is an emirp because it is prime and its reverse (980210202112199) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-991211202012089 is a prime.

It is not a weakly prime, because it can be changed into another prime (991211202012019) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 495605601006044 + 495605601006045.

It is an arithmetic number, because the mean of its divisors is an integer number (495605601006045).

Almost surely, 2^{991211202012089} is an apocalyptic number.

It is an amenable number.

991211202012089 is a deficient number, since it is larger than the sum of its proper divisors (1).

991211202012089 is an equidigital number, since it uses as much as digits as its factorization.

991211202012089 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 93312, while the sum is 47.

The spelling of 991211202012089 in words is "nine hundred ninety-one trillion, two hundred eleven billion, two hundred two million, twelve thousand, eighty-nine".