1210020001991 has 2 divisors, whose sum is σ = 1210020001992. Its totient is φ = 1210020001990.

The previous prime is 1210020001979. The next prime is 1210020002011. The reversal of 1210020001991 is 1991000200121.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 1210020001991 - 2³⁸ = 935142095047 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1210020001991.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1210020001391) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 605010000995 + 605010000996.

It is an arithmetic number, because the mean of its divisors is an integer number (605010000996).

Almost surely, 2^{1210020001991} is an apocalyptic number.

1210020001991 is a deficient number, since it is larger than the sum of its proper divisors (1).

1210020001991 is an equidigital number, since it uses as much as digits as its factorization.

1210020001991 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 324, while the sum is 26.

The spelling of 1210020001991 in words is "one trillion, two hundred ten billion, twenty million, one thousand, nine hundred ninety-one".