261728863 has 4 divisors (see below), whose sum is σ = 285522408. Its totient is φ = 237935320.

The previous prime is 261728849. The next prime is 261728903. The reversal of 261728863 is 368827162.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 261728863 - 2²⁵ = 228174431 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261728813) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 11896756 + ... + 11896777.

It is an arithmetic number, because the mean of its divisors is an integer number (71380602).

Almost surely, 2^261728863 is an apocalyptic number.

261728863 is a deficient number, since it is larger than the sum of its proper divisors (23793545).

261728863 is a wasteful number, since it uses less digits than its factorization.

261728863 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23793544.

The product of its digits is 193536, while the sum is 43.

The square root of 261728863 is about 16178.0364383321. The cubic root of 261728863 is about 639.6619821509.

The spelling of 261728863 in words is "two hundred sixty-one million, seven hundred twenty-eight thousand, eight hundred sixty-three".