1211894009 has 2 divisors, whose sum is σ = 1211894010. Its totient is φ = 1211894008.

The previous prime is 1211894003. The next prime is 1211894017. The reversal of 1211894009 is 9004981121.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1123590400 + 88303609 = 33520^2 + 9397^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1211894009 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1211894009.

It is not a weakly prime, because it can be changed into another prime (1211894003) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 605947004 + 605947005.

It is an arithmetic number, because the mean of its divisors is an integer number (605947005).

Almost surely, 2^1211894009 is an apocalyptic number.

It is an amenable number.

1211894009 is a deficient number, since it is larger than the sum of its proper divisors (1).

1211894009 is an equidigital number, since it uses as much as digits as its factorization.

1211894009 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 5184, while the sum is 35.

The square root of 1211894009 is about 34812.2680818128. The cubic root of 1211894009 is about 1066.1579414727.

The spelling of 1211894009 in words is "one billion, two hundred eleven million, eight hundred ninety-four thousand, nine".