261240 has 64 divisors (see below), whose sum is σ = 898560. Its totient is φ = 59520.

The previous prime is 261229. The next prime is 261241. The reversal of 261240 is 42162.

261240 = T₄₉ + T₅₀ + ... + T₁₁₈.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a zygodrome in base 2.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261241) 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, 685 + ... + 995.

It is an arithmetic number, because the mean of its divisors is an integer number (14040).

2²⁶¹²⁴⁰ is an apocalyptic number.

261240 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 261240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (449280).

261240 is an abundant number, since it is smaller than the sum of its proper divisors (637320).

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

261240 is a wasteful number, since it uses less digits than its factorization.

261240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 332 (or 328 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 15.

The square root of 261240 is about 511.1164250931. The cubic root of 261240 is about 63.9263475635.

Multiplying 261240 by its sum of digits (15), we get a triangular number (3918600 = T₂₇₉₉).

The spelling of 261240 in words is "two hundred sixty-one thousand, two hundred forty".