18905521 has 4 divisors (see below), whose sum is σ = 18929700. Its totient is φ = 18881344.

The previous prime is 18905501. The next prime is 18905539. The reversal of 18905521 is 12550981.

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 9363600 + 9541921 = 3060^2 + 3089^2 .

It is a cyclic number.

It is not a de Polignac number, because 18905521 - 2¹⁵ = 18872753 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18905501) 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, 10876 + ... + 12493.

It is an arithmetic number, because the mean of its divisors is an integer number (4732425).

Almost surely, 2^18905521 is an apocalyptic number.

It is an amenable number.

18905521 is a deficient number, since it is larger than the sum of its proper divisors (24179).

18905521 is an equidigital number, since it uses as much as digits as its factorization.

18905521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24178.

The product of its (nonzero) digits is 3600, while the sum is 31.

The square root of 18905521 is about 4348.0479528174. The cubic root of 18905521 is about 266.3971351299.

The spelling of 18905521 in words is "eighteen million, nine hundred five thousand, five hundred twenty-one".