18010821 has 4 divisors (see below), whose sum is σ = 24014432. Its totient is φ = 12007212.

The previous prime is 18010819. The next prime is 18010829. The reversal of 18010821 is 12801081.

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.

It is not a de Polignac number, because 18010821 - 2¹ = 18010819 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 (18010829) 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, 3001801 + ... + 3001806.

It is an arithmetic number, because the mean of its divisors is an integer number (6003608).

Almost surely, 2^18010821 is an apocalyptic number.

It is an amenable number.

18010821 is a deficient number, since it is larger than the sum of its proper divisors (6003611).

18010821 is an equidigital number, since it uses as much as digits as its factorization.

18010821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6003610.

The product of its (nonzero) digits is 128, while the sum is 21.

The square root of 18010821 is about 4243.9157625947. The cubic root of 18010821 is about 262.1266456462.

The spelling of 18010821 in words is "eighteen million, ten thousand, eight hundred twenty-one".