2181779217 has 6 divisors (see below), whose sum is σ = 3151458882. Its totient is φ = 1454519472.

The previous prime is 2181779213. The next prime is 2181779221. The reversal of 2181779217 is 7129771812.

It is an interprime number because it is at equal distance from previous prime (2181779213) and next prime (2181779221).

It can be written as a sum of positive squares in only one way, i.e., 1499315841 + 682463376 = 38721^2 + 26124^2 .

It is not a de Polignac number, because 2181779217 - 2² = 2181779213 is a prime.

It is not an unprimeable number, because it can be changed into a prime (2181779213) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 121209948 + ... + 121209965.

It is an arithmetic number, because the mean of its divisors is an integer number (525243147).

Almost surely, 2^2181779217 is an apocalyptic number.

It is an amenable number.

2181779217 is a deficient number, since it is larger than the sum of its proper divisors (969679665).

2181779217 is a wasteful number, since it uses less digits than its factorization.

2181779217 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 242419919 (or 242419916 counting only the distinct ones).

The product of its digits is 98784, while the sum is 45.

The square root of 2181779217 is about 46709.5195543692. The cubic root of 2181779217 is about 1296.9909134713.

The spelling of 2181779217 in words is "two billion, one hundred eighty-one million, seven hundred seventy-nine thousand, two hundred seventeen".