2161775261 has 4 divisors (see below), whose sum is σ = 2162758752. Its totient is φ = 2160791772.

The previous prime is 2161775251. The next prime is 2161775299. The reversal of 2161775261 is 1625771612.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 2161775261 - 2²⁶ = 2094666397 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2161775251) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 488441 + ... + 492846.

It is an arithmetic number, because the mean of its divisors is an integer number (540689688).

Almost surely, 2^2161775261 is an apocalyptic number.

It is an amenable number.

2161775261 is a deficient number, since it is larger than the sum of its proper divisors (983491).

2161775261 is an equidigital number, since it uses as much as digits as its factorization.

2161775261 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 983490.

The product of its digits is 35280, while the sum is 38.

The square root of 2161775261 is about 46494.8949993437. The cubic root of 2161775261 is about 1293.0148544404.

The spelling of 2161775261 in words is "two billion, one hundred sixty-one million, seven hundred seventy-five thousand, two hundred sixty-one".