2161040261 has 2 divisors, whose sum is σ = 2161040262. Its totient is φ = 2161040260.

The previous prime is 2161040257. The next prime is 2161040263. The reversal of 2161040261 is 1620401612.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 2150084161 + 10956100 = 46369^2 + 3310^2 .

It is a cyclic number.

It is not a de Polignac number, because 2161040261 - 2² = 2161040257 is a prime.

Together with 2161040263, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2161040263) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1080520130 + 1080520131.

It is an arithmetic number, because the mean of its divisors is an integer number (1080520131).

Almost surely, 2^2161040261 is an apocalyptic number.

It is an amenable number.

2161040261 is a deficient number, since it is larger than the sum of its proper divisors (1).

2161040261 is an equidigital number, since it uses as much as digits as its factorization.

2161040261 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 576, while the sum is 23.

The square root of 2161040261 is about 46486.9902338278. The cubic root of 2161040261 is about 1292.8682968614.

Adding to 2161040261 its reverse (1620401612), we get a palindrome (3781441873).

The spelling of 2161040261 in words is "two billion, one hundred sixty-one million, forty thousand, two hundred sixty-one".