66357521 has 2 divisors, whose sum is σ = 66357522. Its totient is φ = 66357520.

The previous prime is 66357517. The next prime is 66357527. The reversal of 66357521 is 12575366.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 49547521 + 16810000 = 7039^2 + 4100^2 .

It is a cyclic number.

It is not a de Polignac number, because 66357521 - 2² = 66357517 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 (66357527) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33178760 + 33178761.

It is an arithmetic number, because the mean of its divisors is an integer number (33178761).

Almost surely, 2^66357521 is an apocalyptic number.

It is an amenable number.

66357521 is a deficient number, since it is larger than the sum of its proper divisors (1).

66357521 is an equidigital number, since it uses as much as digits as its factorization.

66357521 is an evil number, because the sum of its binary digits is even.

The product of its digits is 37800, while the sum is 35.

The square root of 66357521 is about 8146.0125828530. The cubic root of 66357521 is about 404.8523996004.

The spelling of 66357521 in words is "sixty-six million, three hundred fifty-seven thousand, five hundred twenty-one".