261535640 has 32 divisors (see below), whose sum is σ = 596522880. Its totient is φ = 103180032.

The previous prime is 261535621. The next prime is 261535649. The reversal of 261535640 is 46535162.

It is a junction number, because it is equal to n+sod(n) for n = 261535597 and 261535606.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261535649) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 41864 + ... + 47703.

It is an arithmetic number, because the mean of its divisors is an integer number (18641340).

Almost surely, 2^261535640 is an apocalyptic number.

261535640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

261535640 is an abundant number, since it is smaller than the sum of its proper divisors (334987240).

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

261535640 is a wasteful number, since it uses less digits than its factorization.

261535640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 89651 (or 89647 counting only the distinct ones).

The product of its (nonzero) digits is 21600, while the sum is 32.

The square root of 261535640 is about 16172.0635665335. The cubic root of 261535640 is about 639.5045318876.

The spelling of 261535640 in words is "two hundred sixty-one million, five hundred thirty-five thousand, six hundred forty".