66072521 has 2 divisors, whose sum is σ = 66072522. Its totient is φ = 66072520.

The previous prime is 66072473. The next prime is 66072547. The reversal of 66072521 is 12527066.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 43414921 + 22657600 = 6589^2 + 4760^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66072521 is a prime.

It is not a weakly prime, because it can be changed into another prime (66072581) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33036260 + 33036261.

It is an arithmetic number, because the mean of its divisors is an integer number (33036261).

Almost surely, 2^66072521 is an apocalyptic number.

It is an amenable number.

66072521 is a deficient number, since it is larger than the sum of its proper divisors (1).

66072521 is an equidigital number, since it uses as much as digits as its factorization.

66072521 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 5040, while the sum is 29.

The square root of 66072521 is about 8128.5005382297. The cubic root of 66072521 is about 404.2719654406.

Adding to 66072521 its reverse (12527066), we get a palindrome (78599587).

The spelling of 66072521 in words is "sixty-six million, seventy-two thousand, five hundred twenty-one".