66758621 has 2 divisors, whose sum is σ = 66758622. Its totient is φ = 66758620.

The previous prime is 66758611. The next prime is 66758623. The reversal of 66758621 is 12685766.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 57547396 + 9211225 = 7586^2 + 3035^2 .

It is a cyclic number.

It is not a de Polignac number, because 66758621 - 2⁶ = 66758557 is a prime.

Together with 66758623, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66758623) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33379310 + 33379311.

It is an arithmetic number, because the mean of its divisors is an integer number (33379311).

Almost surely, 2^66758621 is an apocalyptic number.

It is an amenable number.

66758621 is a deficient number, since it is larger than the sum of its proper divisors (1).

66758621 is an equidigital number, since it uses as much as digits as its factorization.

66758621 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 120960, while the sum is 41.

The square root of 66758621 is about 8170.5948987819. The cubic root of 66758621 is about 405.6664756660. Note that the first 3 decimals are identical.

The spelling of 66758621 in words is "sixty-six million, seven hundred fifty-eight thousand, six hundred twenty-one".