18261689 has 8 divisors (see below), whose sum is σ = 19479528. Its totient is φ = 17059840.

The previous prime is 18261673. The next prime is 18261731. The reversal of 18261689 is 98616281.

It can be written as a sum of positive squares in 4 ways, for example, as 4326400 + 13935289 = 2080^2 + 3733^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 18261689 - 2⁴ = 18261673 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18261389) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1592 + ... + 6249.

It is an arithmetic number, because the mean of its divisors is an integer number (2434941).

Almost surely, 2^18261689 is an apocalyptic number.

It is an amenable number.

18261689 is a deficient number, since it is larger than the sum of its proper divisors (1217839).

18261689 is a wasteful number, since it uses less digits than its factorization.

18261689 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7995.

The product of its digits is 41472, while the sum is 41.

The square root of 18261689 is about 4273.3697476348. The cubic root of 18261689 is about 263.3380694906.

The spelling of 18261689 in words is "eighteen million, two hundred sixty-one thousand, six hundred eighty-nine".