261811560 has 64 divisors (see below), whose sum is σ = 831643200. Its totient is φ = 65709056.

The previous prime is 261811549. The next prime is 261811579. The reversal of 261811560 is 65118162.

261811560 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is a Harshad number since it is a multiple of its sum of digits (30).

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, 62130 + ... + 66209.

It is an arithmetic number, because the mean of its divisors is an integer number (12994425).

Almost surely, 2^261811560 is an apocalyptic number.

261811560 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

261811560 is an abundant number, since it is smaller than the sum of its proper divisors (569831640).

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

261811560 is a wasteful number, since it uses less digits than its factorization.

261811560 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 128370 (or 128366 counting only the distinct ones).

The product of its (nonzero) digits is 2880, while the sum is 30.

The square root of 261811560 is about 16180.5920781657. The cubic root of 261811560 is about 639.7293451921.

The spelling of 261811560 in words is "two hundred sixty-one million, eight hundred eleven thousand, five hundred sixty".