1211101001261 has 2 divisors, whose sum is σ = 1211101001262. Its totient is φ = 1211101001260.

The previous prime is 1211101001237. The next prime is 1211101001263. The reversal of 1211101001261 is 1621001011121.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1197733248100 + 13367753161 = 1094410^2 + 115619^2 .

It is an emirp because it is prime and its reverse (1621001011121) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1211101001261 - 2⁶ = 1211101001197 is a prime.

Together with 1211101001263, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1211101001263) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 605550500630 + 605550500631.

It is an arithmetic number, because the mean of its divisors is an integer number (605550500631).

Almost surely, 2^{1211101001261} is an apocalyptic number.

It is an amenable number.

1211101001261 is a deficient number, since it is larger than the sum of its proper divisors (1).

1211101001261 is an equidigital number, since it uses as much as digits as its factorization.

1211101001261 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 24, while the sum is 17.

Adding to 1211101001261 its reverse (1621001011121), we get a palindrome (2832102012382).

The spelling of 1211101001261 in words is "one trillion, two hundred eleven billion, one hundred one million, one thousand, two hundred sixty-one".