261855685125 has 48 divisors (see below), whose sum is σ = 472403982960. Its totient is φ = 139548240000.

The previous prime is 261855685103. The next prime is 261855685219. The reversal of 261855685125 is 521586558162.

It is a happy number.

261855685125 is a `hidden beast` number, since 2 + 6 + 1 + 8 + 5 + 568 + 51 + 25 = 666.

It can be written as a sum of positive squares in 8 ways, for example, as 155173754241 + 106681930884 = 393921^2 + 326622^2 .

It is not a de Polignac number, because 261855685125 - 2⁵ = 261855685093 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 1374171 + ... + 1553079.

It is an arithmetic number, because the mean of its divisors is an integer number (9841749645).

Almost surely, 2^261855685125 is an apocalyptic number.

261855685125 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

261855685125 is a deficient number, since it is larger than the sum of its proper divisors (210548297835).

261855685125 is a wasteful number, since it uses less digits than its factorization.

261855685125 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 180231 (or 180218 counting only the distinct ones).

The product of its digits is 5760000, while the sum is 54.

The spelling of 261855685125 in words is "two hundred sixty-one billion, eight hundred fifty-five million, six hundred eighty-five thousand, one hundred twenty-five".