261873782784 has 182 divisors, whose sum is σ = 785175220626. Its totient is φ = 87290265600.

The previous prime is 261873782783. The next prime is 261873782809. The reversal of 261873782784 is 487287378162.

It is a happy number.

261873782784 is a `hidden beast` number, since 2 + 6 + 187 + 378 + 2 + 7 + 84 = 666.

It can be written as a sum of positive squares in only one way, i.e., 259855257600 + 2018525184 = 509760^2 + 44928^2 .

It is a super-2 number, since 2×261873782784² (a number of 24 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261873782783) by changing a digit.

It is a polite number, since it can be written in 13 ways as a sum of consecutive naturals, for example, 2942134 + ... + 3029834.

Almost surely, 2^261873782784 is an apocalyptic number.

261873782784 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 261873782784, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (392587610313).

261873782784 is an abundant number, since it is smaller than the sum of its proper divisors (523301437842).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

261873782784 is an frugal number, since it uses more digits than its factorization.

261873782784 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 87743 (or 87706 counting only the distinct ones).

The product of its digits is 50577408, while the sum is 63.

The spelling of 261873782784 in words is "two hundred sixty-one billion, eight hundred seventy-three million, seven hundred eighty-two thousand, seven hundred eighty-four".