1317116721 has 4 divisors (see below), whose sum is σ = 1756155632. Its totient is φ = 878077812.

The previous prime is 1317116711. The next prime is 1317116761. The reversal of 1317116721 is 1276117131.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 1317116721 - 2¹⁰ = 1317115697 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1317116711) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 219519451 + ... + 219519456.

It is an arithmetic number, because the mean of its divisors is an integer number (439038908).

Almost surely, 2^1317116721 is an apocalyptic number.

It is an amenable number.

1317116721 is a deficient number, since it is larger than the sum of its proper divisors (439038911).

1317116721 is an equidigital number, since it uses as much as digits as its factorization.

1317116721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 439038910.

The product of its digits is 1764, while the sum is 30.

The square root of 1317116721 is about 36292.1027359948. The cubic root of 1317116721 is about 1096.1620298857.

It can be divided in two parts, 13171 and 16721, that added together give a palindrome (29892).

The spelling of 1317116721 in words is "one billion, three hundred seventeen million, one hundred sixteen thousand, seven hundred twenty-one".