1216505085 has 8 divisors (see below), whose sum is σ = 1946408160. Its totient is φ = 648802704.

The previous prime is 1216505009. The next prime is 1216505107. The reversal of 1216505085 is 5805056121.

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

It is not a de Polignac number, because 1216505085 - 2⁷ = 1216504957 is a prime.

It is a Smith number, since the sum of its digits (33) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 40550155 + ... + 40550184.

It is an arithmetic number, because the mean of its divisors is an integer number (243301020).

Almost surely, 2^1216505085 is an apocalyptic number.

1216505085 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1216505085 is a deficient number, since it is larger than the sum of its proper divisors (729903075).

1216505085 is an equidigital number, since it uses as much as digits as its factorization.

1216505085 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 81100347.

The product of its (nonzero) digits is 12000, while the sum is 33.

The square root of 1216505085 is about 34878.4329493170. The cubic root of 1216505085 is about 1067.5084207918.

The spelling of 1216505085 in words is "one billion, two hundred sixteen million, five hundred five thousand, eighty-five".