261669666 has 16 divisors (see below), whose sum is σ = 546093504. Its totient is φ = 83430864.

The previous prime is 261669649. The next prime is 261669671. The reversal of 261669666 is 666966162.

It is a happy number.

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 7 ways as a sum of consecutive naturals, for example, 947941 + ... + 948216.

It is an arithmetic number, because the mean of its divisors is an integer number (34130844).

Almost surely, 2^261669666 is an apocalyptic number.

261669666 is an abundant number, since it is smaller than the sum of its proper divisors (284423838).

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

261669666 is a wasteful number, since it uses less digits than its factorization.

261669666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1896185.

The product of its digits is 839808, while the sum is 48.

The square root of 261669666 is about 16176.2067865121. The cubic root of 261669666 is about 639.6137529451.

The spelling of 261669666 in words is "two hundred sixty-one million, six hundred sixty-nine thousand, six hundred sixty-six".