261661056 has 32 divisors (see below), whose sum is σ = 695038200. Its totient is φ = 87220224.

The previous prime is 261661033. The next prime is 261661061. The reversal of 261661056 is 650166162.

It is a tau number, because it is divible by the number of its divisors (32).

It is a hoax number, since the sum of its digits (33) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 340321 + ... + 341088.

Almost surely, 2^261661056 is an apocalyptic number.

It is an amenable number.

261661056 is an abundant number, since it is smaller than the sum of its proper divisors (433377144).

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

261661056 is an equidigital number, since it uses as much as digits as its factorization.

261661056 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 681426 (or 681414 counting only the distinct ones).

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

The square root of 261661056 is about 16175.9406527101. The cubic root of 261661056 is about 639.6067375672.

The spelling of 261661056 in words is "two hundred sixty-one million, six hundred sixty-one thousand, fifty-six".