261995387 has 2 divisors, whose sum is σ = 261995388. Its totient is φ = 261995386.

The previous prime is 261995333. The next prime is 261995399. The reversal of 261995387 is 783599162.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 261995387 - 2⁸ = 261995131 is a prime.

It is not a weakly prime, because it can be changed into another prime (261995287) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130997693 + 130997694.

It is an arithmetic number, because the mean of its divisors is an integer number (130997694).

Almost surely, 2^261995387 is an apocalyptic number.

261995387 is a deficient number, since it is larger than the sum of its proper divisors (1).

261995387 is an equidigital number, since it uses as much as digits as its factorization.

261995387 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 816480, while the sum is 50.

The square root of 261995387 is about 16186.2715595655. The cubic root of 261995387 is about 639.8790355693.

The spelling of 261995387 in words is "two hundred sixty-one million, nine hundred ninety-five thousand, three hundred eighty-seven".