261998856 has 192 divisors, whose sum is σ = 859622400. Its totient is φ = 70502400.

The previous prime is 261998827. The next prime is 261998857. The reversal of 261998856 is 658899162.

It is a happy number.

261998856 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261998857) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 640380 + ... + 640788.

It is an arithmetic number, because the mean of its divisors is an integer number (4477200).

Almost surely, 2^261998856 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 261998856, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (429811200).

261998856 is an abundant number, since it is smaller than the sum of its proper divisors (597623544).

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

261998856 is a wasteful number, since it uses less digits than its factorization.

261998856 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 500 (or 493 counting only the distinct ones).

The product of its digits is 1866240, while the sum is 54.

The square root of 261998856 is about 16186.3787179221. The cubic root of 261998856 is about 639.8818597037.

It can be divided in two parts, 2619 and 98856, that added together give a triangular number (101475 = T₄₅₀).

The spelling of 261998856 in words is "two hundred sixty-one million, nine hundred ninety-eight thousand, eight hundred fifty-six".