261688351778280 has 288 divisors, whose sum is σ = 994869250408800. Its totient is φ = 59480320580352.

The previous prime is 261688351778279. The next prime is 261688351778297. The reversal of 261688351778280 is 82877153886162.

261688351778280 is a `hidden beast` number, since 2 + 6 + 1 + 6 + 8 + 83 + 517 + 7 + 8 + 28 + 0 = 666.

261688351778280 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a Harshad number since it is a multiple of its sum of digits (72).

It is a junction number, because it is equal to n+sod(n) for n = 261688351778199 and 261688351778208.

It is an unprimeable number.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 38280822 + ... + 44595941.

It is an arithmetic number, because the mean of its divisors is an integer number (3454407119475).

Almost surely, 2^{261688351778280} is an apocalyptic number.

261688351778280 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

261688351778280 is an abundant number, since it is smaller than the sum of its proper divisors (733180898630520).

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

261688351778280 is a wasteful number, since it uses less digits than its factorization.

261688351778280 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 82876973 (or 82876959 counting only the distinct ones).

The product of its (nonzero) digits is 433520640, while the sum is 72.

The spelling of 261688351778280 in words is "two hundred sixty-one trillion, six hundred eighty-eight billion, three hundred fifty-one million, seven hundred seventy-eight thousand, two hundred eighty".