261155659986 has 48 divisors (see below), whose sum is σ = 609466417560. Its totient is φ = 80341977600.

The previous prime is 261155659981. The next prime is 261155659987. The reversal of 261155659986 is 689956551162.

261155659986 is a `hidden beast` number, since 2 + 61 + 1 + 5 + 565 + 9 + 9 + 8 + 6 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 246294830961 + 14860829025 = 496281^2 + 121905^2 .

It is a super-3 number, since 3×261155659986³ (a number of 35 digits) contains 333 as substring.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (261155659981) 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, 1336170 + ... + 1519098.

Almost surely, 2^261155659986 is an apocalyptic number.

261155659986 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

261155659986 is an abundant number, since it is smaller than the sum of its proper divisors (348310757574).

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

261155659986 is a wasteful number, since it uses less digits than its factorization.

261155659986 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 189051 (or 189048 counting only the distinct ones).

The product of its digits is 34992000, while the sum is 63.

The spelling of 261155659986 in words is "two hundred sixty-one billion, one hundred fifty-five million, six hundred fifty-nine thousand, nine hundred eighty-six".