261131644800 has 768 divisors, whose sum is σ = 1037305483200. Its totient is φ = 63771770880.

The previous prime is 261131644783. The next prime is 261131644811. The reversal of 261131644800 is 8446131162.

261131644800 is a `hidden beast` number, since 2 + 6 + 1 + 1 + 3 + 1 + 644 + 8 + 0 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 153877552 + ... + 153879248.

Almost surely, 2^261131644800 is an apocalyptic number.

261131644800 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 261131644800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (518652741600).

261131644800 is an abundant number, since it is smaller than the sum of its proper divisors (776173838400).

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

261131644800 is a wasteful number, since it uses less digits than its factorization.

261131644800 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1880 (or 1857 counting only the distinct ones).

The product of its (nonzero) digits is 27648, while the sum is 36.

Adding to 261131644800 its reverse (8446131162), we get a palindrome (269577775962).

The spelling of 261131644800 in words is "two hundred sixty-one billion, one hundred thirty-one million, six hundred forty-four thousand, eight hundred".