2181020689 has 4 divisors (see below), whose sum is σ = 2182570020. Its totient is φ = 2179471360.

The previous prime is 2181020663. The next prime is 2181020711. The reversal of 2181020689 is 9860201812.

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 292683664 + 1888337025 = 17108^2 + 43455^2 .

It is a cyclic number.

It is not a de Polignac number, because 2181020689 - 2²³ = 2172632081 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2181020189) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 772552 + ... + 775369.

It is an arithmetic number, because the mean of its divisors is an integer number (545642505).

Almost surely, 2^2181020689 is an apocalyptic number.

It is an amenable number.

2181020689 is a deficient number, since it is larger than the sum of its proper divisors (1549331).

2181020689 is a wasteful number, since it uses less digits than its factorization.

2181020689 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1549330.

The product of its (nonzero) digits is 13824, while the sum is 37.

The square root of 2181020689 is about 46701.3992188671. The cubic root of 2181020689 is about 1296.8405899877.

The spelling of 2181020689 in words is "two billion, one hundred eighty-one million, twenty thousand, six hundred eighty-nine".