261963565 has 8 divisors (see below), whose sum is σ = 314448480. Its totient is φ = 209509392.

The previous prime is 261963551. The next prime is 261963593. The reversal of 261963565 is 565369162.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 261963565 - 2⁷ = 261963437 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 20406 + ... + 30664.

It is an arithmetic number, because the mean of its divisors is an integer number (39306060).

Almost surely, 2^261963565 is an apocalyptic number.

It is an amenable number.

261963565 is a deficient number, since it is larger than the sum of its proper divisors (52484915).

261963565 is a wasteful number, since it uses less digits than its factorization.

261963565 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15371.

The product of its digits is 291600, while the sum is 43.

The square root of 261963565 is about 16185.2885361985. The cubic root of 261963565 is about 639.8531279183.

The spelling of 261963565 in words is "two hundred sixty-one million, nine hundred sixty-three thousand, five hundred sixty-five".