261664242859 has 4 divisors (see below), whose sum is σ = 265248684616. Its totient is φ = 258079801104.

The previous prime is 261664242857. The next prime is 261664242901. The reversal of 261664242859 is 958242466162.

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 261664242859 - 2¹ = 261664242857 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (261664242857) 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, 1792220769 + ... + 1792220914.

It is an arithmetic number, because the mean of its divisors is an integer number (66312171154).

Almost surely, 2^261664242859 is an apocalyptic number.

261664242859 is a deficient number, since it is larger than the sum of its proper divisors (3584441757).

261664242859 is an equidigital number, since it uses as much as digits as its factorization.

261664242859 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3584441756.

The product of its digits is 9953280, while the sum is 55.

The spelling of 261664242859 in words is "two hundred sixty-one billion, six hundred sixty-four million, two hundred forty-two thousand, eight hundred fifty-nine".