1216001666 has 8 divisors (see below), whose sum is σ = 1989820944. Its totient is φ = 552728020.

The previous prime is 1216001627. The next prime is 1216001671. The reversal of 1216001666 is 6661006121.

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

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 27636380 + ... + 27636423.

It is an arithmetic number, because the mean of its divisors is an integer number (248727618).

Almost surely, 2^1216001666 is an apocalyptic number.

1216001666 is a deficient number, since it is larger than the sum of its proper divisors (773819278).

1216001666 is a wasteful number, since it uses less digits than its factorization.

1216001666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 55272816.

The product of its (nonzero) digits is 2592, while the sum is 29.

The square root of 1216001666 is about 34871.2154362305. The cubic root of 1216001666 is about 1067.3611469400.

Adding to 1216001666 its reverse (6661006121), we get a palindrome (7877007787).

The spelling of 1216001666 in words is "one billion, two hundred sixteen million, one thousand, six hundred sixty-six".