1211111081 has 2 divisors, whose sum is σ = 1211111082. Its totient is φ = 1211111080.

The previous prime is 1211111063. The next prime is 1211111101. The reversal of 1211111081 is 1801111121.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1027779481 + 183331600 = 32059^2 + 13540^2 .

It is a cyclic number.

It is not a de Polignac number, because 1211111081 - 2¹⁸ = 1210848937 is a prime.

It is a super-3 number, since 3×1211111081³ (a number of 28 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is not a weakly prime, because it can be changed into another prime (1211111381) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 605555540 + 605555541.

It is an arithmetic number, because the mean of its divisors is an integer number (605555541).

Almost surely, 2^1211111081 is an apocalyptic number.

It is an amenable number.

1211111081 is a deficient number, since it is larger than the sum of its proper divisors (1).

1211111081 is an equidigital number, since it uses as much as digits as its factorization.

1211111081 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 16, while the sum is 17.

The square root of 1211111081 is about 34801.0212637503. The cubic root of 1211111081 is about 1065.9282996290.

The spelling of 1211111081 in words is "one billion, two hundred eleven million, one hundred eleven thousand, eighty-one".