8181521 has 2 divisors, whose sum is σ = 8181522. Its totient is φ = 8181520.

The previous prime is 8181517. The next prime is 8181527. The reversal of 8181521 is 1251818.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 5013121 + 3168400 = 2239^2 + 1780^2 .

It is a cyclic number.

It is not a de Polignac number, because 8181521 - 2² = 8181517 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (8181527) 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 as a sum of consecutive naturals, namely, 4090760 + 4090761.

It is an arithmetic number, because the mean of its divisors is an integer number (4090761).

Almost surely, 2^8181521 is an apocalyptic number.

It is an amenable number.

8181521 is a deficient number, since it is larger than the sum of its proper divisors (1).

8181521 is an equidigital number, since it uses as much as digits as its factorization.

8181521 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 640, while the sum is 26.

The square root of 8181521 is about 2860.3358194450. The cubic root of 8181521 is about 201.5013761459.

The spelling of 8181521 in words is "eight million, one hundred eighty-one thousand, five hundred twenty-one".