1211212243991 has 2 divisors, whose sum is σ = 1211212243992. Its totient is φ = 1211212243990.

The previous prime is 1211212243957. The next prime is 1211212244063. The reversal of 1211212243991 is 1993422121121.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 1211212243991 - 2¹⁰ = 1211212242967 is a prime.

It is a Sophie Germain prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1211212240991) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 605606121995 + 605606121996.

It is an arithmetic number, because the mean of its divisors is an integer number (605606121996).

Almost surely, 2^{1211212243991} is an apocalyptic number.

1211212243991 is a deficient number, since it is larger than the sum of its proper divisors (1).

1211212243991 is an equidigital number, since it uses as much as digits as its factorization.

1211212243991 is an evil number, because the sum of its binary digits is even.

The product of its digits is 15552, while the sum is 38.

The spelling of 1211212243991 in words is "one trillion, two hundred eleven billion, two hundred twelve million, two hundred forty-three thousand, nine hundred ninety-one".