18939845 has 4 divisors (see below), whose sum is σ = 22727820. Its totient is φ = 15151872.

The previous prime is 18939841. The next prime is 18939847. The reversal of 18939845 is 54893981.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 54893981 = 379 ⋅144839.

It can be written as a sum of positive squares in 2 ways, for example, as 2666689 + 16273156 = 1633^2 + 4034^2 .

It is a cyclic number.

It is not a de Polignac number, because 18939845 - 2² = 18939841 is a prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 18939845.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18939841) 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, 1893980 + ... + 1893989.

It is an arithmetic number, because the mean of its divisors is an integer number (5681955).

Almost surely, 2^18939845 is an apocalyptic number.

It is an amenable number.

18939845 is a deficient number, since it is larger than the sum of its proper divisors (3787975).

18939845 is an equidigital number, since it uses as much as digits as its factorization.

18939845 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3787974.

The product of its digits is 311040, while the sum is 47.

The square root of 18939845 is about 4351.9932215021. The cubic root of 18939845 is about 266.5582571489.

The spelling of 18939845 in words is "eighteen million, nine hundred thirty-nine thousand, eight hundred forty-five".