2156918161 has 2 divisors, whose sum is σ = 2156918162. Its totient is φ = 2156918160.

The previous prime is 2156918149. The next prime is 2156918191. The reversal of 2156918161 is 1618196512.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 2125210000 + 31708161 = 46100^2 + 5631^2 .

It is a cyclic number.

It is not a de Polignac number, because 2156918161 - 2⁹ = 2156917649 is a prime.

It is not a weakly prime, because it can be changed into another prime (2156918191) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1078459080 + 1078459081.

It is an arithmetic number, because the mean of its divisors is an integer number (1078459081).

Almost surely, 2^2156918161 is an apocalyptic number.

It is an amenable number.

2156918161 is a deficient number, since it is larger than the sum of its proper divisors (1).

2156918161 is an equidigital number, since it uses as much as digits as its factorization.

2156918161 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 25920, while the sum is 40.

The square root of 2156918161 is about 46442.6330110600. The cubic root of 2156918161 is about 1292.0457416942.

The spelling of 2156918161 in words is "two billion, one hundred fifty-six million, nine hundred eighteen thousand, one hundred sixty-one".