261646660 has 48 divisors (see below), whose sum is σ = 634677120. Its totient is φ = 89546240.

The previous prime is 261646633. The next prime is 261646699. The reversal of 261646660 is 66646162.

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 15 ways as a sum of consecutive naturals, for example, 31240 + ... + 38719.

It is an arithmetic number, because the mean of its divisors is an integer number (13222440).

Almost surely, 2^261646660 is an apocalyptic number.

261646660 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

261646660 is an abundant number, since it is smaller than the sum of its proper divisors (373030460).

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

261646660 is a wasteful number, since it uses less digits than its factorization.

261646660 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 69996 (or 69994 counting only the distinct ones).

The product of its (nonzero) digits is 62208, while the sum is 37.

The square root of 261646660 is about 16175.4956647393. The cubic root of 261646660 is about 639.5950074463.

The spelling of 261646660 in words is "two hundred sixty-one million, six hundred forty-six thousand, six hundred sixty".