261866765 has 16 divisors (see below), whose sum is σ = 327269376. Its totient is φ = 200928000.

The previous prime is 261866741. The next prime is 261866777. The reversal of 261866765 is 567668162.

It is not a de Polignac number, because 261866765 - 2⁶ = 261866701 is a prime.

It is a super-2 number, since 2×261866765² = 137148405223130450, which contains 22 as substring.

It is a Duffinian 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 15 ways as a sum of consecutive naturals, for example, 10040 + ... + 24990.

It is an arithmetic number, because the mean of its divisors is an integer number (20454336).

Almost surely, 2^261866765 is an apocalyptic number.

It is an amenable number.

261866765 is a deficient number, since it is larger than the sum of its proper divisors (65402611).

261866765 is a wasteful number, since it uses less digits than its factorization.

261866765 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15100.

The product of its digits is 725760, while the sum is 47.

The square root of 261866765 is about 16182.2978899784. The cubic root of 261866765 is about 639.7743059985.

The spelling of 261866765 in words is "two hundred sixty-one million, eight hundred sixty-six thousand, seven hundred sixty-five".