1216511211 has 16 divisors (see below), whose sum is σ = 1719563904. Its totient is φ = 762351744.

The previous prime is 1216511209. The next prime is 1216511251. The reversal of 1216511211 is 1121156121.

It is not a de Polignac number, because 1216511211 - 2¹ = 1216511209 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1216511251) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 27756 + ... + 56598.

It is an arithmetic number, because the mean of its divisors is an integer number (107472744).

Almost surely, 2^1216511211 is an apocalyptic number.

1216511211 is a deficient number, since it is larger than the sum of its proper divisors (503052693).

1216511211 is a wasteful number, since it uses less digits than its factorization.

1216511211 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 29690.

The product of its digits is 120, while the sum is 21.

The square root of 1216511211 is about 34878.5207685188. The cubic root of 1216511211 is about 1067.5102126861.

Adding to 1216511211 its reverse (1121156121), we get a palindrome (2337667332).

The spelling of 1216511211 in words is "one billion, two hundred sixteen million, five hundred eleven thousand, two hundred eleven".