261779856 has 80 divisors (see below), whose sum is σ = 735536256. Its totient is φ = 79746048.

The previous prime is 261779849. The next prime is 261779857. The reversal of 261779856 is 658977162.

261779856 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a junction number, because it is equal to n+sod(n) for n = 261779799 and 261779808.

It is not an unprimeable number, because it can be changed into a prime (261779857) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 62236 + ... + 66308.

Almost surely, 2^261779856 is an apocalyptic number.

261779856 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 261779856, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (367768128).

261779856 is an abundant number, since it is smaller than the sum of its proper divisors (473756400).

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

261779856 is a wasteful number, since it uses less digits than its factorization.

261779856 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4200 (or 4194 counting only the distinct ones).

The product of its digits is 1270080, while the sum is 51.

The square root of 261779856 is about 16179.6123562958. The cubic root of 261779856 is about 639.7035215324.

The spelling of 261779856 in words is "two hundred sixty-one million, seven hundred seventy-nine thousand, eight hundred fifty-six".