2180391688261 has 4 divisors (see below), whose sum is σ = 2191459666572. Its totient is φ = 2169323709952.

The previous prime is 2180391688253. The next prime is 2180391688289. The reversal of 2180391688261 is 1628861930812.

It is a happy number.

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

It can be written as a sum of positive squares in 2 ways, for example, as 1396369985761 + 784021702500 = 1181681^2 + 885450^2 .

It is a cyclic number.

It is not a de Polignac number, because 2180391688261 - 2³ = 2180391688253 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 (2180391688201) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5533988860 + ... + 5533989253.

It is an arithmetic number, because the mean of its divisors is an integer number (547864916643).

Almost surely, 2^{2180391688261} is an apocalyptic number.

It is an amenable number.

2180391688261 is a deficient number, since it is larger than the sum of its proper divisors (11067978311).

2180391688261 is a wasteful number, since it uses less digits than its factorization.

2180391688261 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11067978310.

The product of its (nonzero) digits is 1990656, while the sum is 55.

The spelling of 2180391688261 in words is "two trillion, one hundred eighty billion, three hundred ninety-one million, six hundred eighty-eight thousand, two hundred sixty-one".