261531312 has 80 divisors (see below), whose sum is σ = 788616192. Its totient is φ = 73128960.

The previous prime is 261531311. The next prime is 261531323. The reversal of 261531312 is 213135162.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is not an unprimeable number, because it can be changed into a prime (261531311) 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, 7512 + ... + 24072.

Almost surely, 2^261531312 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 261531312, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (394308096).

261531312 is an abundant number, since it is smaller than the sum of its proper divisors (527084880).

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

261531312 is a wasteful number, since it uses less digits than its factorization.

261531312 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16626 (or 16620 counting only the distinct ones).

The product of its digits is 1080, while the sum is 24.

The square root of 261531312 is about 16171.9297549798. The cubic root of 261531312 is about 639.5010042729.

Adding to 261531312 its reverse (213135162), we get a palindrome (474666474).

The spelling of 261531312 in words is "two hundred sixty-one million, five hundred thirty-one thousand, three hundred twelve".