261155580 has 48 divisors (see below), whose sum is σ = 835699200. Its totient is φ = 59692608.

The previous prime is 261155569. The next prime is 261155597. The reversal of 261155580 is 85551162.

It is a super-3 number, since 3×261155580³ (a number of 26 digits) contains 333 as substring.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 310480 + ... + 311319.

It is an arithmetic number, because the mean of its divisors is an integer number (17410400).

Almost surely, 2^261155580 is an apocalyptic number.

261155580 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

261155580 is an abundant number, since it is smaller than the sum of its proper divisors (574543620).

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

261155580 is a wasteful number, since it uses less digits than its factorization.

261155580 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 621818 (or 621816 counting only the distinct ones).

The product of its (nonzero) digits is 12000, while the sum is 33.

The square root of 261155580 is about 16160.3087841786. The cubic root of 261155580 is about 639.1946086461.

The spelling of 261155580 in words is "two hundred sixty-one million, one hundred fifty-five thousand, five hundred eighty".