261181564 has 36 divisors (see below), whose sum is σ = 533909880. Its totient is φ = 111468000.

The previous prime is 261181561. The next prime is 261181567. The reversal of 261181564 is 465181162.

261181564 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an interprime number because it is at equal distance from previous prime (261181561) and next prime (261181567).

It is a hoax number, since the sum of its digits (34) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261181561) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 46542 + ... + 51850.

It is an arithmetic number, because the mean of its divisors is an integer number (14830830).

Almost surely, 2^261181564 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 261181564, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (266954940).

261181564 is an abundant number, since it is smaller than the sum of its proper divisors (272728316).

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

261181564 is a wasteful number, since it uses less digits than its factorization.

261181564 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5578 (or 5569 counting only the distinct ones).

The product of its digits is 11520, while the sum is 34.

The square root of 261181564 is about 16161.1127092165. The cubic root of 261181564 is about 639.2158070979.

The spelling of 261181564 in words is "two hundred sixty-one million, one hundred eighty-one thousand, five hundred sixty-four".