18505521 has 12 divisors (see below), whose sum is σ = 26771472. Its totient is φ = 12317976.

The previous prime is 18505519. The next prime is 18505541. The reversal of 18505521 is 12550581.

It is not a de Polignac number, because 18505521 - 2¹ = 18505519 is a prime.

It is not an unprimeable number, because it can be changed into a prime (18505541) 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 11 ways as a sum of consecutive naturals, for example, 7030 + ... + 9296.

It is an arithmetic number, because the mean of its divisors is an integer number (2230956).

Almost surely, 2^18505521 is an apocalyptic number.

18505521 is the 2721-st heptagonal number.

It is an amenable number.

18505521 is a deficient number, since it is larger than the sum of its proper divisors (8265951).

18505521 is a wasteful number, since it uses less digits than its factorization.

18505521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3180 (or 3177 counting only the distinct ones).

The product of its (nonzero) digits is 2000, while the sum is 27.

The square root of 18505521 is about 4301.8043888582. The cubic root of 18505521 is about 264.5049306843.

The spelling of 18505521 in words is "eighteen million, five hundred five thousand, five hundred twenty-one".