66207521 has 2 divisors, whose sum is σ = 66207522. Its totient is φ = 66207520.

The previous prime is 66207481. The next prime is 66207539. The reversal of 66207521 is 12570266.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 42393121 + 23814400 = 6511^2 + 4880^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66207521 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (66207821) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33103760 + 33103761.

It is an arithmetic number, because the mean of its divisors is an integer number (33103761).

Almost surely, 2^66207521 is an apocalyptic number.

It is an amenable number.

66207521 is a deficient number, since it is larger than the sum of its proper divisors (1).

66207521 is an equidigital number, since it uses as much as digits as its factorization.

66207521 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 66207521 is about 8136.8004153967. The cubic root of 66207521 is about 404.5471155640.

Adding to 66207521 its reverse (12570266), we get a palindrome (78777787).

It can be divided in two parts, 6620 and 7521, that added together give a palindrome (14141).

The spelling of 66207521 in words is "sixty-six million, two hundred seven thousand, five hundred twenty-one".