261966231 has 20 divisors (see below), whose sum is σ = 391883184. Its totient is φ = 174398400.

The previous prime is 261966223. The next prime is 261966233. The reversal of 261966231 is 132669162.

It is a happy number.

261966231 is a `hidden beast` number, since 2 + 619 + 6 + 6 + 2 + 31 = 666.

It is not a de Polignac number, because 261966231 - 2³ = 261966223 is a prime.

It is a super-3 number, since 3×261966231³ (a number of 26 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261966233) 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 in 19 ways as a sum of consecutive naturals, for example, 69526 + ... + 73196.

Almost surely, 2^261966231 is an apocalyptic number.

261966231 is a deficient number, since it is larger than the sum of its proper divisors (129916953).

261966231 is an equidigital number, since it uses as much as digits as its factorization.

261966231 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4564 (or 4555 counting only the distinct ones).

The product of its digits is 23328, while the sum is 36.

The square root of 261966231 is about 16185.3708947308. The cubic root of 261966231 is about 639.8552985035.

The spelling of 261966231 in words is "two hundred sixty-one million, nine hundred sixty-six thousand, two hundred thirty-one".