261531163 has 2 divisors, whose sum is σ = 261531164. Its totient is φ = 261531162.

The previous prime is 261531161. The next prime is 261531191. The reversal of 261531163 is 361135162.

It is an a-pointer prime, because the next prime (261531191) can be obtained adding 261531163 to its sum of digits (28).

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 261531163 - 2¹ = 261531161 is a prime.

Together with 261531161, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (261531161) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130765581 + 130765582.

It is an arithmetic number, because the mean of its divisors is an integer number (130765582).

Almost surely, 2^261531163 is an apocalyptic number.

261531163 is a deficient number, since it is larger than the sum of its proper divisors (1).

261531163 is an equidigital number, since it uses as much as digits as its factorization.

261531163 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3240, while the sum is 28.

The square root of 261531163 is about 16171.9251482314. The cubic root of 261531163 is about 639.5008828270.

The spelling of 261531163 in words is "two hundred sixty-one million, five hundred thirty-one thousand, one hundred sixty-three".