18493861 has 4 divisors (see below), whose sum is σ = 18535500. Its totient is φ = 18452224.

The previous prime is 18493823. The next prime is 18493877. The reversal of 18493861 is 16839481.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 16839481 = 3119 ⋅5399.

It can be written as a sum of positive squares in 2 ways, for example, as 3632836 + 14861025 = 1906^2 + 3855^2 .

It is a cyclic number.

It is not a de Polignac number, because 18493861 - 2⁷ = 18493733 is a prime.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18493261) 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, 20146 + ... + 21043.

It is an arithmetic number, because the mean of its divisors is an integer number (4633875).

Almost surely, 2^18493861 is an apocalyptic number.

It is an amenable number.

18493861 is a deficient number, since it is larger than the sum of its proper divisors (41639).

18493861 is an equidigital number, since it uses as much as digits as its factorization.

18493861 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 41638.

The product of its digits is 41472, while the sum is 40.

The square root of 18493861 is about 4300.4489300537. The cubic root of 18493861 is about 264.4493657266.

The spelling of 18493861 in words is "eighteen million, four hundred ninety-three thousand, eight hundred sixty-one".