261131663 has 16 divisors (see below), whose sum is σ = 286144320. Its totient is φ = 236860416.

The previous prime is 261131659. The next prime is 261131669. The reversal of 261131663 is 366131162.

It is a happy number.

It is not a de Polignac number, because 261131663 - 2² = 261131659 is a prime.

It is a super-3 number, since 3×261131663³ (a number of 26 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261131669) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 197318 + ... + 198636.

It is an arithmetic number, because the mean of its divisors is an integer number (17884020).

Almost surely, 2^261131663 is an apocalyptic number.

261131663 is a deficient number, since it is larger than the sum of its proper divisors (25012657).

261131663 is a wasteful number, since it uses less digits than its factorization.

261131663 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1586.

The product of its digits is 3888, while the sum is 29.

The square root of 261131663 is about 16159.5687751870. The cubic root of 261131663 is about 639.1750952662.

The spelling of 261131663 in words is "two hundred sixty-one million, one hundred thirty-one thousand, six hundred sixty-three".