261599563 has 2 divisors, whose sum is σ = 261599564. Its totient is φ = 261599562.

The previous prime is 261599551. The next prime is 261599579. The reversal of 261599563 is 365995162.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 261599563 - 2⁵ = 261599531 is a prime.

It is not a weakly prime, because it can be changed into another prime (261599593) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130799781 + 130799782.

It is an arithmetic number, because the mean of its divisors is an integer number (130799782).

Almost surely, 2^261599563 is an apocalyptic number.

261599563 is a deficient number, since it is larger than the sum of its proper divisors (1).

261599563 is an equidigital number, since it uses as much as digits as its factorization.

261599563 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 437400, while the sum is 46.

The square root of 261599563 is about 16174.0397860275. The cubic root of 261599563 is about 639.5566289531.

The spelling of 261599563 in words is "two hundred sixty-one million, five hundred ninety-nine thousand, five hundred sixty-three".