261642312243 has 80 divisors (see below), whose sum is σ = 425784189600. Its totient is φ = 159152947200.

The previous prime is 261642312241. The next prime is 261642312263. The reversal of 261642312243 is 342213246162.

261642312243 is a `hidden beast` number, since 2 + 6 + 1 + 6 + 423 + 1 + 224 + 3 = 666.

It is not a de Polignac number, because 261642312243 - 2¹ = 261642312241 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 261642312198 and 261642312207.

It is not an unprimeable number, because it can be changed into a prime (261642312241) by changing a digit.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 78593203 + ... + 78596531.

It is an arithmetic number, because the mean of its divisors is an integer number (5322302370).

Almost surely, 2^261642312243 is an apocalyptic number.

261642312243 is a deficient number, since it is larger than the sum of its proper divisors (164141877357).

261642312243 is a wasteful number, since it uses less digits than its factorization.

261642312243 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4194 (or 4185 counting only the distinct ones).

The product of its digits is 82944, while the sum is 36.

The spelling of 261642312243 in words is "two hundred sixty-one billion, six hundred forty-two million, three hundred twelve thousand, two hundred forty-three".