18928661 has 4 divisors (see below), whose sum is σ = 18942924. Its totient is φ = 18914400.

The previous prime is 18928649. The next prime is 18928669. The reversal of 18928661 is 16682981.

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 11122225 + 7806436 = 3335^2 + 2794^2 .

It is a cyclic number.

It is not a de Polignac number, because 18928661 - 2⁶ = 18928597 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 (18928669) 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, 4910 + ... + 7871.

It is an arithmetic number, because the mean of its divisors is an integer number (4735731).

Almost surely, 2^18928661 is an apocalyptic number.

It is an amenable number.

18928661 is a deficient number, since it is larger than the sum of its proper divisors (14263).

18928661 is a wasteful number, since it uses less digits than its factorization.

18928661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14262.

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

The square root of 18928661 is about 4350.7081032862. The cubic root of 18928661 is about 266.5057791668.

The spelling of 18928661 in words is "eighteen million, nine hundred twenty-eight thousand, six hundred sixty-one".