1216329805 has 8 divisors (see below), whose sum is σ = 1459855512. Its totient is φ = 972890688.

The previous prime is 1216329799. The next prime is 1216329839. The reversal of 1216329805 is 5089236121.

It can be written as a sum of positive squares in 4 ways, for example, as 4384836 + 1211944969 = 2094^2 + 34813^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1216329805 - 2³ = 1216329797 is a prime.

It is a super-3 number, since 3×1216329805³ (a number of 28 digits) contains 333 as substring.

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 7 ways as a sum of consecutive naturals, for example, 14859 + ... + 51511.

It is an arithmetic number, because the mean of its divisors is an integer number (182481939).

Almost surely, 2^1216329805 is an apocalyptic number.

It is an amenable number.

1216329805 is a deficient number, since it is larger than the sum of its proper divisors (243525707).

1216329805 is an equidigital number, since it uses as much as digits as its factorization.

1216329805 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 43295.

The product of its (nonzero) digits is 25920, while the sum is 37.

The square root of 1216329805 is about 34875.9201312309. The cubic root of 1216329805 is about 1067.4571477185.

The spelling of 1216329805 in words is "one billion, two hundred sixteen million, three hundred twenty-nine thousand, eight hundred five".