261840283985 has 24 divisors (see below), whose sum is σ = 371702727360. Its totient is φ = 176504433504.

The previous prime is 261840283981. The next prime is 261840283993. The reversal of 261840283985 is 589382048162.

It is a happy number.

It is not a de Polignac number, because 261840283985 - 2² = 261840283981 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 261840283985.

It is not an unprimeable number, because it can be changed into a prime (261840283981) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 9042629 + ... + 9071538.

It is an arithmetic number, because the mean of its divisors is an integer number (15487613640).

Almost surely, 2^261840283985 is an apocalyptic number.

It is an amenable number.

261840283985 is a deficient number, since it is larger than the sum of its proper divisors (109862443375).

261840283985 is a wasteful number, since it uses less digits than its factorization.

261840283985 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18114245 (or 18114238 counting only the distinct ones).

The product of its (nonzero) digits is 6635520, while the sum is 56.

The spelling of 261840283985 in words is "two hundred sixty-one billion, eight hundred forty million, two hundred eighty-three thousand, nine hundred eighty-five".