261655604 has 48 divisors (see below), whose sum is σ = 538513920. Its totient is φ = 108906240.

The previous prime is 261655573. The next prime is 261655607. The reversal of 261655604 is 406556162.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261655607) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 363557 + ... + 364275.

It is an arithmetic number, because the mean of its divisors is an integer number (11219040).

Almost surely, 2^261655604 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 261655604, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (269256960).

261655604 is an abundant number, since it is smaller than the sum of its proper divisors (276858316).

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

261655604 is a wasteful number, since it uses less digits than its factorization.

261655604 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1088 (or 1086 counting only the distinct ones).

The product of its (nonzero) digits is 43200, while the sum is 35.

The square root of 261655604 is about 16175.7721299479. The cubic root of 261655604 is about 639.6022952297.

The spelling of 261655604 in words is "two hundred sixty-one million, six hundred fifty-five thousand, six hundred four".