261247056 has 160 divisors (see below), whose sum is σ = 802234368. Its totient is φ = 71715840.

The previous prime is 261247043. The next prime is 261247067. The reversal of 261247056 is 650742162.

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 31 ways as a sum of consecutive naturals, for example, 1121116 + ... + 1121348.

Almost surely, 2^261247056 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 261247056, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (401117184).

261247056 is an abundant number, since it is smaller than the sum of its proper divisors (540987312).

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

261247056 is a wasteful number, since it uses less digits than its factorization.

261247056 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 369 (or 363 counting only the distinct ones).

The product of its (nonzero) digits is 20160, while the sum is 33.

The square root of 261247056 is about 16163.1388040813. The cubic root of 261247056 is about 639.2692310103.

The spelling of 261247056 in words is "two hundred sixty-one million, two hundred forty-seven thousand, fifty-six".