261090816 has 120 divisors (see below), whose sum is σ = 809356680. Its totient is φ = 74575872.

The previous prime is 261090803. The next prime is 261090877. The reversal of 261090816 is 618090162.

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, 73530 + ... + 76998.

It is an arithmetic number, because the mean of its divisors is an integer number (6744639).

Almost surely, 2^261090816 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 261090816, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (404678340).

261090816 is an abundant number, since it is smaller than the sum of its proper divisors (548265864).

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

261090816 is an equidigital number, since it uses as much as digits as its factorization.

261090816 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3504 (or 3481 counting only the distinct ones).

The product of its (nonzero) digits is 5184, while the sum is 33.

The square root of 261090816 is about 16158.3048615874. The cubic root of 261090816 is about 639.1417662982.

The spelling of 261090816 in words is "two hundred sixty-one million, ninety thousand, eight hundred sixteen".