18239945 has 4 divisors (see below), whose sum is σ = 21887940. Its totient is φ = 14591952.

The previous prime is 18239941. The next prime is 18239953. The reversal of 18239945 is 54993281.

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 10106041 + 8133904 = 3179^2 + 2852^2 .

It is a cyclic number.

It is not a de Polignac number, because 18239945 - 2² = 18239941 is a prime.

It is not an unprimeable number, because it can be changed into a prime (18239941) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1823990 + ... + 1823999.

It is an arithmetic number, because the mean of its divisors is an integer number (5471985).

Almost surely, 2^18239945 is an apocalyptic number.

It is an amenable number.

18239945 is a deficient number, since it is larger than the sum of its proper divisors (3647995).

18239945 is an equidigital number, since it uses as much as digits as its factorization.

18239945 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3647994.

The product of its digits is 77760, while the sum is 41.

The square root of 18239945 is about 4270.8248617802. The cubic root of 18239945 is about 263.2335100287.

The spelling of 18239945 in words is "eighteen million, two hundred thirty-nine thousand, nine hundred forty-five".