18128993 has 2 divisors, whose sum is σ = 18128994. Its totient is φ = 18128992.

The previous prime is 18128963. The next prime is 18129071. The reversal of 18128993 is 39982181.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17875984 + 253009 = 4228^2 + 503^2 .

It is a cyclic number.

It is not a de Polignac number, because 18128993 - 2¹⁰ = 18127969 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 18128993.

It is not a weakly prime, because it can be changed into another prime (18128933) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9064496 + 9064497.

It is an arithmetic number, because the mean of its divisors is an integer number (9064497).

Almost surely, 2^18128993 is an apocalyptic number.

It is an amenable number.

18128993 is a deficient number, since it is larger than the sum of its proper divisors (1).

18128993 is an equidigital number, since it uses as much as digits as its factorization.

18128993 is an evil number, because the sum of its binary digits is even.

The product of its digits is 31104, while the sum is 41.

The square root of 18128993 is about 4257.8155197237. The cubic root of 18128993 is about 262.6986819337.

The spelling of 18128993 in words is "eighteen million, one hundred twenty-eight thousand, nine hundred ninety-three".