261666506011660 has 96 divisors (see below), whose sum is σ = 558782429587200. Its totient is φ = 102904556122368.

The previous prime is 261666506011613. The next prime is 261666506011679. The reversal of 261666506011660 is 66110605666162.

It is a super-3 number, since 3×261666506011660³ (a number of 44 digits) contains 333 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 261666506011598 and 261666506011607.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 10322544666 + ... + 10322570014.

It is an arithmetic number, because the mean of its divisors is an integer number (5820650308200).

Almost surely, 2^{261666506011660} is an apocalyptic number.

261666506011660 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

261666506011660 is an abundant number, since it is smaller than the sum of its proper divisors (297115923575540).

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

261666506011660 is a wasteful number, since it uses less digits than its factorization.

261666506011660 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40055 (or 40053 counting only the distinct ones).

The product of its (nonzero) digits is 2799360, while the sum is 52.

The spelling of 261666506011660 in words is "two hundred sixty-one trillion, six hundred sixty-six billion, five hundred six million, eleven thousand, six hundred sixty".