1211320999991 has 2 divisors, whose sum is σ = 1211320999992. Its totient is φ = 1211320999990.

The previous prime is 1211320999961. The next prime is 1211321000023. The reversal of 1211320999991 is 1999990231121.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1211320999991 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1211320999961) 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, 605660499995 + 605660499996.

It is an arithmetic number, because the mean of its divisors is an integer number (605660499996).

Almost surely, 2^{1211320999991} is an apocalyptic number.

1211320999991 is a deficient number, since it is larger than the sum of its proper divisors (1).

1211320999991 is an equidigital number, since it uses as much as digits as its factorization.

1211320999991 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 708588, while the sum is 56.

The spelling of 1211320999991 in words is "one trillion, two hundred eleven billion, three hundred twenty million, nine hundred ninety-nine thousand, nine hundred ninety-one".