261155165 has 8 divisors (see below), whose sum is σ = 313486008. Its totient is φ = 208857600.

The previous prime is 261155149. The next prime is 261155189. The reversal of 261155165 is 561551162.

It can be written as a sum of positive squares in 4 ways, for example, as 6497401 + 254657764 = 2549^2 + 15958^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 261155165 - 2⁴ = 261155149 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 14789 + ... + 27221.

It is an arithmetic number, because the mean of its divisors is an integer number (39185751).

Almost surely, 2^261155165 is an apocalyptic number.

It is an amenable number.

261155165 is a deficient number, since it is larger than the sum of its proper divisors (52330843).

261155165 is a wasteful number, since it uses less digits than its factorization.

261155165 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16639.

The product of its digits is 9000, while the sum is 32.

The square root of 261155165 is about 16160.2959440723. The cubic root of 261155165 is about 639.1942700665.

The spelling of 261155165 in words is "two hundred sixty-one million, one hundred fifty-five thousand, one hundred sixty-five".