66538481 has 2 divisors, whose sum is σ = 66538482. Its totient is φ = 66538480.

The previous prime is 66538421. The next prime is 66538519. The reversal of 66538481 is 18483566.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 64240225 + 2298256 = 8015^2 + 1516^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66538481 is a prime.

It is a super-2 number, since 2×66538481² = 8854738907574722, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (66538421) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33269240 + 33269241.

It is an arithmetic number, because the mean of its divisors is an integer number (33269241).

Almost surely, 2^66538481 is an apocalyptic number.

It is an amenable number.

66538481 is a deficient number, since it is larger than the sum of its proper divisors (1).

66538481 is an equidigital number, since it uses as much as digits as its factorization.

66538481 is an evil number, because the sum of its binary digits is even.

The product of its digits is 138240, while the sum is 41.

The square root of 66538481 is about 8157.1122954144. The cubic root of 66538481 is about 405.2200825874.

The spelling of 66538481 in words is "sixty-six million, five hundred thirty-eight thousand, four hundred eighty-one".