18021013 has 4 divisors (see below), whose sum is σ = 18602368. Its totient is φ = 17439660.

The previous prime is 18020993. The next prime is 18021053. The reversal of 18021013 is 31012081.

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: 31012081 = 881 ⋅35201.

It is a cyclic number.

It is not a de Polignac number, because 18021013 - 2⁹ = 18020501 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 (18021053) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 290631 + ... + 290692.

It is an arithmetic number, because the mean of its divisors is an integer number (4650592).

Almost surely, 2^18021013 is an apocalyptic number.

It is an amenable number.

18021013 is a deficient number, since it is larger than the sum of its proper divisors (581355).

18021013 is an equidigital number, since it uses as much as digits as its factorization.

18021013 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 581354.

The product of its (nonzero) digits is 48, while the sum is 16.

The square root of 18021013 is about 4245.1163706075. The cubic root of 18021013 is about 262.1760805757.

Adding to 18021013 its reverse (31012081), we get a palindrome (49033094).

The spelling of 18021013 in words is "eighteen million, twenty-one thousand, thirteen".