1216661011 has 2 divisors, whose sum is σ = 1216661012. Its totient is φ = 1216661010.

The previous prime is 1216660987. The next prime is 1216661021. The reversal of 1216661011 is 1101666121.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 1216661011 - 2⁵ = 1216660979 is a prime.

It is not a weakly prime, because it can be changed into another prime (1216661021) 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, 608330505 + 608330506.

It is an arithmetic number, because the mean of its divisors is an integer number (608330506).

Almost surely, 2^1216661011 is an apocalyptic number.

1216661011 is a deficient number, since it is larger than the sum of its proper divisors (1).

1216661011 is an equidigital number, since it uses as much as digits as its factorization.

1216661011 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 432, while the sum is 25.

The square root of 1216661011 is about 34880.6681558711. The cubic root of 1216661011 is about 1067.5540282754.

The spelling of 1216661011 in words is "one billion, two hundred sixteen million, six hundred sixty-one thousand, eleven".