261193391 has 2 divisors, whose sum is σ = 261193392. Its totient is φ = 261193390.

The previous prime is 261193367. The next prime is 261193483. The reversal of 261193391 is 193391162.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-261193391 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (261193091) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130596695 + 130596696.

It is an arithmetic number, because the mean of its divisors is an integer number (130596696).

Almost surely, 2^261193391 is an apocalyptic number.

261193391 is a deficient number, since it is larger than the sum of its proper divisors (1).

261193391 is an equidigital number, since it uses as much as digits as its factorization.

261193391 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 8748, while the sum is 35.

The square root of 261193391 is about 16161.4786142853. The cubic root of 261193391 is about 639.2254554196.

The spelling of 261193391 in words is "two hundred sixty-one million, one hundred ninety-three thousand, three hundred ninety-one".