18928109 has 2 divisors, whose sum is σ = 18928110. Its totient is φ = 18928108.

The previous prime is 18928069. The next prime is 18928121. The reversal of 18928109 is 90182981.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15015625 + 3912484 = 3875^2 + 1978^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18928109 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18928139) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9464054 + 9464055.

It is an arithmetic number, because the mean of its divisors is an integer number (9464055).

Almost surely, 2^18928109 is an apocalyptic number.

It is an amenable number.

18928109 is a deficient number, since it is larger than the sum of its proper divisors (1).

18928109 is an equidigital number, since it uses as much as digits as its factorization.

18928109 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 10368, while the sum is 38.

The square root of 18928109 is about 4350.6446648744. The cubic root of 18928109 is about 266.5031885166.

It can be divided in two parts, 1892 and 8109, that added together give a palindrome (10001).

The spelling of 18928109 in words is "eighteen million, nine hundred twenty-eight thousand, one hundred nine".