261689904 has 120 divisors (see below), whose sum is σ = 846686880. Its totient is φ = 73903104.

The previous prime is 261689893. The next prime is 261689917. The reversal of 261689904 is 409986162.

It is a happy number.

It is a self number, because there is not a number n which added to its sum of digits gives 261689904.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 88254 + ... + 91170.

It is an arithmetic number, because the mean of its divisors is an integer number (7055724).

Almost surely, 2^261689904 is an apocalyptic number.

261689904 is a gapful number since it is divisible by the number (24) 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 261689904, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (423343440).

261689904 is an abundant number, since it is smaller than the sum of its proper divisors (584996976).

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

261689904 is a wasteful number, since it uses less digits than its factorization.

261689904 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3027 (or 3018 counting only the distinct ones).

The product of its (nonzero) digits is 186624, while the sum is 45.

The square root of 261689904 is about 16176.8323228004. The cubic root of 261689904 is about 639.6302421439.

The spelling of 261689904 in words is "two hundred sixty-one million, six hundred eighty-nine thousand, nine hundred four".