261985440 has 96 divisors (see below), whose sum is σ = 827499456. Its totient is φ = 69672960.

The previous prime is 261985439. The next prime is 261985441. The reversal of 261985440 is 44589162.

261985440 is digitally balanced in base 2, 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 (261985439) and next prime (261985441).

It is a tau number, because it is divible by the number of its divisors (96).

It is not an unprimeable number, because it can be changed into a prime (261985441) 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, 322635 + ... + 323445.

It is an arithmetic number, because the mean of its divisors is an integer number (8619786).

Almost surely, 2^261985440 is an apocalyptic number.

261985440 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 261985440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (413749728).

261985440 is an abundant number, since it is smaller than the sum of its proper divisors (565514016).

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

261985440 is a wasteful number, since it uses less digits than its factorization.

261985440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1502 (or 1494 counting only the distinct ones).

The product of its (nonzero) digits is 69120, while the sum is 39.

The square root of 261985440 is about 16185.9642900879. The cubic root of 261985440 is about 639.8709375167.

The spelling of 261985440 in words is "two hundred sixty-one million, nine hundred eighty-five thousand, four hundred forty".