261431984 has 160 divisors (see below), whose sum is σ = 636387840. Its totient is φ = 102502400.

The previous prime is 261431981. The next prime is 261431993. The reversal of 261431984 is 489134162.

It is not an unprimeable number, because it can be changed into a prime (261431981) 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 31 ways as a sum of consecutive naturals, for example, 1995599 + ... + 1995729.

It is an arithmetic number, because the mean of its divisors is an integer number (3977424).

Almost surely, 2^261431984 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 261431984, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (318193920).

261431984 is an abundant number, since it is smaller than the sum of its proper divisors (374955856).

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

261431984 is a wasteful number, since it uses less digits than its factorization.

261431984 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 219 (or 213 counting only the distinct ones).

The product of its digits is 41472, while the sum is 38.

The square root of 261431984 is about 16168.8584631074. The cubic root of 261431984 is about 639.4200344921.

The spelling of 261431984 in words is "two hundred sixty-one million, four hundred thirty-one thousand, nine hundred eighty-four".