261131040 has 120 divisors (see below), whose sum is σ = 921620700. Its totient is φ = 69631488.

The previous prime is 261131027. The next prime is 261131047. The reversal of 261131040 is 40131162.

It is a happy number.

261131040 is a `hidden beast` number, since 2 + 611 + 3 + 10 + 40 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 258952464 + 2178576 = 16092^2 + 1476^2 .

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

It is a Harshad number since it is a multiple of its sum of digits (18).

It is not an unprimeable number, because it can be changed into a prime (261131047) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 2886 + ... + 23034.

Almost surely, 2^261131040 is an apocalyptic number.

261131040 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 261131040, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (460810350).

261131040 is an abundant number, since it is smaller than the sum of its proper divisors (660489660).

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

261131040 is a wasteful number, since it uses less digits than its factorization.

261131040 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20176 (or 20159 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 18.

The square root of 261131040 is about 16159.5494986711. The cubic root of 261131040 is about 639.1745869576.

The spelling of 261131040 in words is "two hundred sixty-one million, one hundred thirty-one thousand, forty".