2191040261 has 2 divisors, whose sum is σ = 2191040262. Its totient is φ = 2191040260.

The previous prime is 2191040251. The next prime is 2191040263. The reversal of 2191040261 is 1620401912.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1953109636 + 237930625 = 44194^2 + 15425^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-2191040261 is a prime.

Together with 2191040263, it forms a pair of twin primes.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 2191040261.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2191040263) 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 as a sum of consecutive naturals, namely, 1095520130 + 1095520131.

It is an arithmetic number, because the mean of its divisors is an integer number (1095520131).

Almost surely, 2^2191040261 is an apocalyptic number.

It is an amenable number.

2191040261 is a deficient number, since it is larger than the sum of its proper divisors (1).

2191040261 is an equidigital number, since it uses as much as digits as its factorization.

2191040261 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 864, while the sum is 26.

The square root of 2191040261 is about 46808.5490161787. The cubic root of 2191040261 is about 1298.8234445614.

The spelling of 2191040261 in words is "two billion, one hundred ninety-one million, forty thousand, two hundred sixty-one".