261123828809 has 4 divisors (see below), whose sum is σ = 274867188240. Its totient is φ = 247380469380.

The previous prime is 261123828803. The next prime is 261123828821. The reversal of 261123828809 is 908828321162.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-261123828809 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (261123828803) 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, 6871679687 + ... + 6871679724.

It is an arithmetic number, because the mean of its divisors is an integer number (68716797060).

Almost surely, 2^261123828809 is an apocalyptic number.

It is an amenable number.

261123828809 is a deficient number, since it is larger than the sum of its proper divisors (13743359431).

261123828809 is a wasteful number, since it uses less digits than its factorization.

261123828809 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13743359430.

The product of its (nonzero) digits is 663552, while the sum is 50.

The spelling of 261123828809 in words is "two hundred sixty-one billion, one hundred twenty-three million, eight hundred twenty-eight thousand, eight hundred nine".