18031821 has 8 divisors (see below), whose sum is σ = 24066240. Its totient is φ = 12009312.

The previous prime is 18031807. The next prime is 18031837. The reversal of 18031821 is 12813081.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 18031821 - 2⁵ = 18031789 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 18031791 and 18031800.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18031121) 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 7 ways as a sum of consecutive naturals, for example, 1536 + ... + 6198.

It is an arithmetic number, because the mean of its divisors is an integer number (3008280).

Almost surely, 2^18031821 is an apocalyptic number.

It is an amenable number.

18031821 is a deficient number, since it is larger than the sum of its proper divisors (6034419).

18031821 is a wasteful number, since it uses less digits than its factorization.

18031821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5955.

The product of its (nonzero) digits is 384, while the sum is 24.

The square root of 18031821 is about 4246.3891719907. The cubic root of 18031821 is about 262.2284829719.

The spelling of 18031821 in words is "eighteen million, thirty-one thousand, eight hundred twenty-one".