1211212219981 has 2 divisors, whose sum is σ = 1211212219982. Its totient is φ = 1211212219980.

The previous prime is 1211212219969. The next prime is 1211212220027. The reversal of 1211212219981 is 1899122121121.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1194941941956 + 16270278025 = 1093134^2 + 127555^2 .

It is an emirp because it is prime and its reverse (1899122121121) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1211212219981 - 2⁷ = 1211212219853 is a prime.

It is a super-2 number, since 2×1211212219981² (a number of 25 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1211212219781) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 605606109990 + 605606109991.

It is an arithmetic number, because the mean of its divisors is an integer number (605606109991).

Almost surely, 2^{1211212219981} is an apocalyptic number.

It is an amenable number.

1211212219981 is a deficient number, since it is larger than the sum of its proper divisors (1).

1211212219981 is an equidigital number, since it uses as much as digits as its factorization.

1211212219981 is an evil number, because the sum of its binary digits is even.

The product of its digits is 10368, while the sum is 40.

The spelling of 1211212219981 in words is "one trillion, two hundred eleven billion, two hundred twelve million, two hundred nineteen thousand, nine hundred eighty-one".