261709056 has 216 divisors, whose sum is σ = 895795264. Its totient is φ = 74649600.

The previous prime is 261709031. The next prime is 261709081. The reversal of 261709056 is 650907162.

It is an interprime number because it is at equal distance from previous prime (261709031) and next prime (261709081).

It is a tau number, because it is divible by the number of its divisors (216).

It is a super-2 number, since 2×261709056² = 136983259984822272, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a self number, because there is not a number n which added to its sum of digits gives 261709056.

It is a congruent number.

It is an unprimeable number.

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 23 ways as a sum of consecutive naturals, for example, 435156 + ... + 435756.

Almost surely, 2^261709056 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 261709056, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (447897632).

261709056 is an abundant number, since it is smaller than the sum of its proper divisors (634086208).

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

261709056 is an frugal number, since it uses more digits than its factorization.

261709056 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 639 (or 613 counting only the distinct ones).

The product of its (nonzero) digits is 22680, while the sum is 36.

The square root of 261709056 is about 16177.4242696419. The cubic root of 261709056 is about 639.6458457259.

The spelling of 261709056 in words is "two hundred sixty-one million, seven hundred nine thousand, fifty-six".