261685536 has 96 divisors (see below), whose sum is σ = 819237888. Its totient is φ = 71512320.

The previous prime is 261685517. The next prime is 261685577. The reversal of 261685536 is 635586162.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (96).

It is a Harshad number since it is a multiple of its sum of digits (42).

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 6991 + ... + 23921.

It is an arithmetic number, because the mean of its divisors is an integer number (8533728).

Almost surely, 2^261685536 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 261685536, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (409618944).

261685536 is an abundant number, since it is smaller than the sum of its proper divisors (557552352).

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

261685536 is a wasteful number, since it uses less digits than its factorization.

261685536 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16974 (or 16966 counting only the distinct ones).

The product of its digits is 259200, while the sum is 42.

The square root of 261685536 is about 16176.6973143470. The cubic root of 261685536 is about 639.6266833257.

The spelling of 261685536 in words is "two hundred sixty-one million, six hundred eighty-five thousand, five hundred thirty-six".