66132721 has 2 divisors, whose sum is σ = 66132722. Its totient is φ = 66132720.

The previous prime is 66132719. The next prime is 66132739. The reversal of 66132721 is 12723166.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 48163600 + 17969121 = 6940^2 + 4239^2 .

It is a cyclic number.

It is not a de Polignac number, because 66132721 - 2¹ = 66132719 is a prime.

Together with 66132719, it forms a pair of twin primes.

It is a self number, because there is not a number n which added to its sum of digits gives 66132721.

It is not a weakly prime, because it can be changed into another prime (66132701) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33066360 + 33066361.

It is an arithmetic number, because the mean of its divisors is an integer number (33066361).

Almost surely, 2^66132721 is an apocalyptic number.

It is an amenable number.

66132721 is a deficient number, since it is larger than the sum of its proper divisors (1).

66132721 is an equidigital number, since it uses as much as digits as its factorization.

66132721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3024, while the sum is 28.

The square root of 66132721 is about 8132.2027151320. The cubic root of 66132721 is about 404.3947082709.

Adding to 66132721 its reverse (12723166), we get a palindrome (78855887).

The spelling of 66132721 in words is "sixty-six million, one hundred thirty-two thousand, seven hundred twenty-one".