261909687312 has 480 divisors, whose sum is σ = 941952211200. Its totient is φ = 66070867968.

The previous prime is 261909687269. The next prime is 261909687317. The reversal of 261909687312 is 213786909162.

261909687312 is a `hidden beast` number, since 2 + 619 + 0 + 9 + 6 + 8 + 7 + 3 + 12 = 666.

It is a super-2 number, since 2×261909687312² (a number of 24 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (261909687317) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 41418583 + ... + 41424905.

It is an arithmetic number, because the mean of its divisors is an integer number (1962400440).

Almost surely, 2^261909687312 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 261909687312, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (470976105600).

261909687312 is an abundant number, since it is smaller than the sum of its proper divisors (680042523888).

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

261909687312 is a wasteful number, since it uses less digits than its factorization.

261909687312 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6495 (or 6486 counting only the distinct ones).

The product of its (nonzero) digits is 1959552, while the sum is 54.

The spelling of 261909687312 in words is "two hundred sixty-one billion, nine hundred nine million, six hundred eighty-seven thousand, three hundred twelve".