261121680 has 120 divisors (see below), whose sum is σ = 905299200. Its totient is φ = 67380480.

The previous prime is 261121673. The next prime is 261121681. The reversal of 261121680 is 86121162.

It is a tau number, because it is divible by the number of its divisors (120).

It is not an unprimeable number, because it can be changed into a prime (261121681) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 16471 + ... + 28169.

It is an arithmetic number, because the mean of its divisors is an integer number (7544160).

Almost surely, 2^261121680 is an apocalyptic number.

261121680 is a gapful number since it is divisible by the number (20) 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 261121680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (452649600).

261121680 is an abundant number, since it is smaller than the sum of its proper divisors (644177520).

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

261121680 is a wasteful number, since it uses less digits than its factorization.

261121680 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11749 (or 11740 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 27.

The square root of 261121680 is about 16159.2598840417. The cubic root of 261121680 is about 639.1669499929.

The spelling of 261121680 in words is "two hundred sixty-one million, one hundred twenty-one thousand, six hundred eighty".