1216011205 has 4 divisors (see below), whose sum is σ = 1459213452. Its totient is φ = 972808960.

The previous prime is 1216011197. The next prime is 1216011217. The reversal of 1216011205 is 5021106121.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 815330916 + 400680289 = 28554^2 + 20017^2 .

It is not a de Polignac number, because 1216011205 - 2³ = 1216011197 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

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, 121601116 + ... + 121601125.

It is an arithmetic number, because the mean of its divisors is an integer number (364803363).

Almost surely, 2^1216011205 is an apocalyptic number.

It is an amenable number.

1216011205 is a deficient number, since it is larger than the sum of its proper divisors (243202247).

1216011205 is an equidigital number, since it uses as much as digits as its factorization.

1216011205 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 243202246.

The product of its (nonzero) digits is 120, while the sum is 19.

The square root of 1216011205 is about 34871.3522106614. The cubic root of 1216011205 is about 1067.3639379261.

Adding to 1216011205 its reverse (5021106121), we get a palindrome (6237117326).

The spelling of 1216011205 in words is "one billion, two hundred sixteen million, eleven thousand, two hundred five".