1216666005 has 32 divisors (see below), whose sum is σ = 2012156544. Its totient is φ = 627284736.

The previous prime is 1216665997. The next prime is 1216666049. The reversal of 1216666005 is 5006666121.

It is not a de Polignac number, because 1216666005 - 2³ = 1216665997 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 80154 + ... + 94116.

It is an arithmetic number, because the mean of its divisors is an integer number (62879892).

Almost surely, 2^1216666005 is an apocalyptic number.

1216666005 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1216666005 is a deficient number, since it is larger than the sum of its proper divisors (795490539).

1216666005 is a wasteful number, since it uses less digits than its factorization.

1216666005 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14165.

The product of its (nonzero) digits is 12960, while the sum is 33.

The square root of 1216666005 is about 34880.7397427291. The cubic root of 1216666005 is about 1067.5554889280. Note that the first 3 decimals are identical.

The spelling of 1216666005 in words is "one billion, two hundred sixteen million, six hundred sixty-six thousand, five".