18021545 has 4 divisors (see below), whose sum is σ = 21625860. Its totient is φ = 14417232.

The previous prime is 18021529. The next prime is 18021569. The reversal of 18021545 is 54512081.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 5938969 + 12082576 = 2437^2 + 3476^2 .

It is a cyclic number.

It is not a de Polignac number, because 18021545 - 2⁴ = 18021529 is a prime.

It is an unprimeable number.

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, 1802150 + ... + 1802159.

It is an arithmetic number, because the mean of its divisors is an integer number (5406465).

Almost surely, 2^18021545 is an apocalyptic number.

It is an amenable number.

18021545 is a deficient number, since it is larger than the sum of its proper divisors (3604315).

18021545 is an equidigital number, since it uses as much as digits as its factorization.

18021545 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3604314.

The product of its (nonzero) digits is 1600, while the sum is 26.

The square root of 18021545 is about 4245.1790303826. The cubic root of 18021545 is about 262.1786604584.

The spelling of 18021545 in words is "eighteen million, twenty-one thousand, five hundred forty-five".