261905604 has 96 divisors (see below), whose sum is σ = 672819840. Its totient is φ = 78962688.

The previous prime is 261905603. The next prime is 261905617. The reversal of 261905604 is 406509162.

261905604 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is not an unprimeable number, because it can be changed into a prime (261905603) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 640152 + ... + 640560.

It is an arithmetic number, because the mean of its divisors is an integer number (7008540).

Almost surely, 2^261905604 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 261905604, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (336409920).

261905604 is an abundant number, since it is smaller than the sum of its proper divisors (410914236).

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

261905604 is a wasteful number, since it uses less digits than its factorization.

261905604 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 549 (or 547 counting only the distinct ones).

The product of its (nonzero) digits is 12960, while the sum is 33.

The square root of 261905604 is about 16183.4978913707. The cubic root of 261905604 is about 639.8059339982.

The spelling of 261905604 in words is "two hundred sixty-one million, nine hundred five thousand, six hundred four".