261431136 has 72 divisors (see below), whose sum is σ = 748140120. Its totient is φ = 86593536.

The previous prime is 261431123. The next prime is 261431141. The reversal of 261431136 is 631134162.

261431136 is a `hidden beast` number, since 2 + 614 + 3 + 11 + 36 = 666.

It is a tau number, because it is divible by the number of its divisors (72).

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 44160 + ... + 49728.

It is an arithmetic number, because the mean of its divisors is an integer number (10390835).

Almost surely, 2^261431136 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 261431136, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (374070060).

261431136 is an abundant number, since it is smaller than the sum of its proper divisors (486708984).

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

261431136 is a wasteful number, since it uses less digits than its factorization.

261431136 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5748 (or 5737 counting only the distinct ones).

The product of its digits is 2592, while the sum is 27.

The square root of 261431136 is about 16168.8322398372. The cubic root of 261431136 is about 639.4193431347.

Adding to 261431136 its reverse (631134162), we get a palindrome (892565298).

The spelling of 261431136 in words is "two hundred sixty-one million, four hundred thirty-one thousand, one hundred thirty-six".