261780 has 24 divisors (see below), whose sum is σ = 733152. Its totient is φ = 69792.

The previous prime is 261773. The next prime is 261787. The reversal of 261780 is 87162.

261780 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is an interprime number because it is at equal distance from previous prime (261773) and next prime (261787).

It is a nialpdrome in base 4.

It is a self number, because there is not a number n which added to its sum of digits gives 261780.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261787) by changing a digit.

261780 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2122 + ... + 2241.

It is an arithmetic number, because the mean of its divisors is an integer number (30548).

2²⁶¹⁷⁸⁰ is an apocalyptic number.

261780 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

261780 is an abundant number, since it is smaller than the sum of its proper divisors (471372).

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

261780 is a wasteful number, since it uses less digits than its factorization.

261780 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4375 (or 4373 counting only the distinct ones).

The product of its (nonzero) digits is 672, while the sum is 24.

The square root of 261780 is about 511.6444077677. The cubic root of 261780 is about 63.9703638829.

The spelling of 261780 in words is "two hundred sixty-one thousand, seven hundred eighty".