66198521 has 2 divisors, whose sum is σ = 66198522. Its totient is φ = 66198520.

The previous prime is 66198497. The next prime is 66198533. The reversal of 66198521 is 12589166.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 58690921 + 7507600 = 7661^2 + 2740^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66198521 is a prime.

It is not a weakly prime, because it can be changed into another prime (66198541) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33099260 + 33099261.

It is an arithmetic number, because the mean of its divisors is an integer number (33099261).

Almost surely, 2^66198521 is an apocalyptic number.

It is an amenable number.

66198521 is a deficient number, since it is larger than the sum of its proper divisors (1).

66198521 is an equidigital number, since it uses as much as digits as its factorization.

66198521 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 25920, while the sum is 38.

The square root of 66198521 is about 8136.2473536637. The cubic root of 66198521 is about 404.5287838650.

The spelling of 66198521 in words is "sixty-six million, one hundred ninety-eight thousand, five hundred twenty-one".