18573521 has 2 divisors, whose sum is σ = 18573522. Its totient is φ = 18573520.

The previous prime is 18573517. The next prime is 18573523. The reversal of 18573521 is 12537581.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18490000 + 83521 = 4300^2 + 289^2 .

It is a cyclic number.

It is not a de Polignac number, because 18573521 - 2² = 18573517 is a prime.

Together with 18573523, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (18573523) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9286760 + 9286761.

It is an arithmetic number, because the mean of its divisors is an integer number (9286761).

Almost surely, 2^18573521 is an apocalyptic number.

It is an amenable number.

18573521 is a deficient number, since it is larger than the sum of its proper divisors (1).

18573521 is an equidigital number, since it uses as much as digits as its factorization.

18573521 is an evil number, because the sum of its binary digits is even.

The product of its digits is 8400, while the sum is 32.

The square root of 18573521 is about 4309.7008016799. The cubic root of 18573521 is about 264.8285160873.

The spelling of 18573521 in words is "eighteen million, five hundred seventy-three thousand, five hundred twenty-one".