7218185718661 has 2 divisors, whose sum is σ = 7218185718662. Its totient is φ = 7218185718660.

The previous prime is 7218185718647. The next prime is 7218185718701. The reversal of 7218185718661 is 1668175818127.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 7156641536100 + 61544182561 = 2675190^2 + 248081^2 .

It is a cyclic number.

It is not a de Polignac number, because 7218185718661 - 2³⁵ = 7183825980293 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 7218185718661.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (7218185715661) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3609092859330 + 3609092859331.

It is an arithmetic number, because the mean of its divisors is an integer number (3609092859331).

Almost surely, 2^{7218185718661} is an apocalyptic number.

It is an amenable number.

7218185718661 is a deficient number, since it is larger than the sum of its proper divisors (1).

7218185718661 is an equidigital number, since it uses as much as digits as its factorization.

7218185718661 is an evil number, because the sum of its binary digits is even.

The product of its digits is 9031680, while the sum is 61.

The spelling of 7218185718661 in words is "seven trillion, two hundred eighteen billion, one hundred eighty-five million, seven hundred eighteen thousand, six hundred sixty-one".