18723109 has 2 divisors, whose sum is σ = 18723110. Its totient is φ = 18723108.

The previous prime is 18723053. The next prime is 18723121. The reversal of 18723109 is 90132781.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 13068225 + 5654884 = 3615^2 + 2378^2 .

It is an emirp because it is prime and its reverse (90132781) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 18723109 - 2⁷ = 18722981 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18723139) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9361554 + 9361555.

It is an arithmetic number, because the mean of its divisors is an integer number (9361555).

Almost surely, 2^18723109 is an apocalyptic number.

It is an amenable number.

18723109 is a deficient number, since it is larger than the sum of its proper divisors (1).

18723109 is an equidigital number, since it uses as much as digits as its factorization.

18723109 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3024, while the sum is 31.

The square root of 18723109 is about 4327.0207995802. The cubic root of 18723109 is about 265.5375773020.

The spelling of 18723109 in words is "eighteen million, seven hundred twenty-three thousand, one hundred nine".