2218105661 has 2 divisors, whose sum is σ = 2218105662. Its totient is φ = 2218105660.

The previous prime is 2218105627. The next prime is 2218105709. The reversal of 2218105661 is 1665018122.

2218105661 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1971804025 + 246301636 = 44405^2 + 15694^2 .

It is a cyclic number.

It is not a de Polignac number, because 2218105661 - 2²⁶ = 2150996797 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2218105361) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1109052830 + 1109052831.

It is an arithmetic number, because the mean of its divisors is an integer number (1109052831).

Almost surely, 2^2218105661 is an apocalyptic number.

It is an amenable number.

2218105661 is a deficient number, since it is larger than the sum of its proper divisors (1).

2218105661 is an equidigital number, since it uses as much as digits as its factorization.

2218105661 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 5760, while the sum is 32.

The square root of 2218105661 is about 47096.7691142397. The cubic root of 2218105661 is about 1304.1495926985.

The spelling of 2218105661 in words is "two billion, two hundred eighteen million, one hundred five thousand, six hundred sixty-one".