1216808291 has 8 divisors (see below), whose sum is σ = 1270007424. Its totient is φ = 1164729280.

The previous prime is 1216808287. The next prime is 1216808309. The reversal of 1216808291 is 1928086121.

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 1216808291 - 2² = 1216808287 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1216808231) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 277811 + ... + 282156.

It is an arithmetic number, because the mean of its divisors is an integer number (158750928).

Almost surely, 2^1216808291 is an apocalyptic number.

1216808291 is a deficient number, since it is larger than the sum of its proper divisors (53199133).

1216808291 is an equidigital number, since it uses as much as digits as its factorization.

1216808291 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 560061.

The product of its (nonzero) digits is 13824, while the sum is 38.

The square root of 1216808291 is about 34882.7792900738. The cubic root of 1216808291 is about 1067.5971032738.

The spelling of 1216808291 in words is "one billion, two hundred sixteen million, eight hundred eight thousand, two hundred ninety-one".