18119821 has 4 divisors (see below), whose sum is σ = 18199872. Its totient is φ = 18039772.

The previous prime is 18119819. The next prime is 18119851. The reversal of 18119821 is 12891181.

18119821 is nontrivially palindromic in base 15.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 12891181 = 163 ⋅79087.

It is a cyclic number.

It is not a de Polignac number, because 18119821 - 2¹ = 18119819 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18119851) 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, 39685 + ... + 40138.

It is an arithmetic number, because the mean of its divisors is an integer number (4549968).

Almost surely, 2^18119821 is an apocalyptic number.

It is an amenable number.

18119821 is a deficient number, since it is larger than the sum of its proper divisors (80051).

18119821 is an equidigital number, since it uses as much as digits as its factorization.

18119821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 80050.

The product of its digits is 1152, while the sum is 31.

The square root of 18119821 is about 4256.7383053225. The cubic root of 18119821 is about 262.6543720858.

It can be divided in two parts, 181 and 19821, that added together give a palindrome (20002).

The spelling of 18119821 in words is "eighteen million, one hundred nineteen thousand, eight hundred twenty-one".