18288661 has 4 divisors (see below), whose sum is σ = 18332524. Its totient is φ = 18244800.

The previous prime is 18288649. The next prime is 18288689. The reversal of 18288661 is 16688281.

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 2047761 + 16240900 = 1431^2 + 4030^2 .

It is a cyclic number.

It is not a de Polignac number, because 18288661 - 2⁷ = 18288533 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 (18288601) 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, 21300 + ... + 22141.

It is an arithmetic number, because the mean of its divisors is an integer number (4583131).

Almost surely, 2^18288661 is an apocalyptic number.

It is an amenable number.

18288661 is a deficient number, since it is larger than the sum of its proper divisors (43863).

18288661 is an equidigital number, since it uses as much as digits as its factorization.

18288661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 43862.

The product of its digits is 36864, while the sum is 40.

The square root of 18288661 is about 4276.5244065713. The cubic root of 18288661 is about 263.4676533500.

The spelling of 18288661 in words is "eighteen million, two hundred eighty-eight thousand, six hundred sixty-one".