261891800 has 144 divisors (see below), whose sum is σ = 678371760. Its totient is φ = 93829120.

The previous prime is 261891797. The next prime is 261891821. The reversal of 261891800 is 8198162.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 1329302 + ... + 1329498.

It is an arithmetic number, because the mean of its divisors is an integer number (4710915).

Almost surely, 2^261891800 is an apocalyptic number.

261891800 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 261891800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (339185880).

261891800 is an abundant number, since it is smaller than the sum of its proper divisors (416479960).

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

261891800 is a wasteful number, since it uses less digits than its factorization.

261891800 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 270 (or 244 counting only the distinct ones).

The product of its (nonzero) digits is 6912, while the sum is 35.

The square root of 261891800 is about 16183.0714019311. The cubic root of 261891800 is about 639.7946932609.

The spelling of 261891800 in words is "two hundred sixty-one million, eight hundred ninety-one thousand, eight hundred".