18020891 has 16 divisors (see below), whose sum is σ = 21648384. Its totient is φ = 14666784.

The previous prime is 18020851. The next prime is 18020897. The reversal of 18020891 is 19802081.

It is a cyclic number.

It is not a de Polignac number, because 18020891 - 2¹⁴ = 18004507 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18020897) 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 15 ways as a sum of consecutive naturals, for example, 27530 + ... + 28176.

It is an arithmetic number, because the mean of its divisors is an integer number (1353024).

Almost surely, 2^18020891 is an apocalyptic number.

18020891 is a deficient number, since it is larger than the sum of its proper divisors (3627493).

18020891 is a wasteful number, since it uses less digits than its factorization.

18020891 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 850.

The product of its (nonzero) digits is 1152, while the sum is 29.

The square root of 18020891 is about 4245.1020011302. The cubic root of 18020891 is about 262.1754889413.

The spelling of 18020891 in words is "eighteen million, twenty thousand, eight hundred ninety-one".