261231536 has 40 divisors (see below), whose sum is σ = 535806480. Its totient is φ = 123169536.

The previous prime is 261231533. The next prime is 261231547. The reversal of 261231536 is 635132162.

It is a Harshad number since it is a multiple of its sum of digits (29).

It is a junction number, because it is equal to n+sod(n) for n = 261231499 and 261231508.

It is not an unprimeable number, because it can be changed into a prime (261231533) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 13406 + ... + 26498.

It is an arithmetic number, because the mean of its divisors is an integer number (13395162).

Almost surely, 2^261231536 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 261231536, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (267903240).

261231536 is an abundant number, since it is smaller than the sum of its proper divisors (274574944).

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

261231536 is a wasteful number, since it uses less digits than its factorization.

261231536 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13173 (or 13167 counting only the distinct ones).

The product of its digits is 6480, while the sum is 29.

The square root of 261231536 is about 16162.6586921830. The cubic root of 261231536 is about 639.2565716588.

Adding to 261231536 its reverse (635132162), we get a palindrome (896363698).

The spelling of 261231536 in words is "two hundred sixty-one million, two hundred thirty-one thousand, five hundred thirty-six".