261644666 has 16 divisors (see below), whose sum is σ = 395756928. Its totient is φ = 129729600.

The previous prime is 261644651. The next prime is 261644683. The reversal of 261644666 is 666446162.

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, 286751 + ... + 287661.

It is an arithmetic number, because the mean of its divisors is an integer number (24734808).

Almost surely, 2^261644666 is an apocalyptic number.

261644666 is a deficient number, since it is larger than the sum of its proper divisors (134112262).

261644666 is a wasteful number, since it uses less digits than its factorization.

261644666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1957.

The product of its digits is 248832, while the sum is 41.

The square root of 261644666 is about 16175.4340281799. The cubic root of 261644666 is about 639.5933826651.

The spelling of 261644666 in words is "two hundred sixty-one million, six hundred forty-four thousand, six hundred sixty-six".