261266777216 has 64 divisors (see below), whose sum is σ = 524966672160. Its totient is φ = 129512908800.

The previous prime is 261266777197. The next prime is 261266777221. The reversal of 261266777216 is 612777662162.

It is a tau number, because it is divible by the number of its divisors (64).

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 14212511 + ... + 14230881.

Almost surely, 2^261266777216 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 261266777216, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (262483336080).

261266777216 is an abundant number, since it is smaller than the sum of its proper divisors (263699894944).

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

261266777216 is a wasteful number, since it uses less digits than its factorization.

261266777216 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19333 (or 19321 counting only the distinct ones).

The product of its digits is 3556224, while the sum is 53.

The spelling of 261266777216 in words is "two hundred sixty-one billion, two hundred sixty-six million, seven hundred seventy-seven thousand, two hundred sixteen".