1216005611 has 4 divisors (see below), whose sum is σ = 1216079424. Its totient is φ = 1215931800.

The previous prime is 1216005601. The next prime is 1216005617. The reversal of 1216005611 is 1165006121.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 1216005611 - 2⁶ = 1216005547 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1216005617) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 326 + ... + 49316.

It is an arithmetic number, because the mean of its divisors is an integer number (304019856).

Almost surely, 2^1216005611 is an apocalyptic number.

1216005611 is a deficient number, since it is larger than the sum of its proper divisors (73813).

1216005611 is an equidigital number, since it uses as much as digits as its factorization.

1216005611 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 73812.

The product of its (nonzero) digits is 360, while the sum is 23.

The square root of 1216005611 is about 34871.2720014628. The cubic root of 1216005611 is about 1067.3623011970.

The spelling of 1216005611 in words is "one billion, two hundred sixteen million, five thousand, six hundred eleven".