261435566 has 16 divisors (see below), whose sum is σ = 448447104. Its totient is φ = 111975864.

The previous prime is 261435547. The next prime is 261435589. The reversal of 261435566 is 665534162.

It is a happy number.

It is a Curzon number.

It is a congruent number.

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, 23381 + ... + 32703.

It is an arithmetic number, because the mean of its divisors is an integer number (28027944).

Almost surely, 2^261435566 is an apocalyptic number.

261435566 is a deficient number, since it is larger than the sum of its proper divisors (187011538).

261435566 is a wasteful number, since it uses less digits than its factorization.

261435566 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11335.

The product of its digits is 129600, while the sum is 38.

The square root of 261435566 is about 16168.9692312157. The cubic root of 261435566 is about 639.4229548082.

The spelling of 261435566 in words is "two hundred sixty-one million, four hundred thirty-five thousand, five hundred sixty-six".