66718121 has 2 divisors, whose sum is σ = 66718122. Its totient is φ = 66718120.

The previous prime is 66718117. The next prime is 66718129. The reversal of 66718121 is 12181766.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 45225625 + 21492496 = 6725^2 + 4636^2 .

It is a cyclic number.

It is not a de Polignac number, because 66718121 - 2² = 66718117 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (66718129) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33359060 + 33359061.

It is an arithmetic number, because the mean of its divisors is an integer number (33359061).

Almost surely, 2^66718121 is an apocalyptic number.

It is an amenable number.

66718121 is a deficient number, since it is larger than the sum of its proper divisors (1).

66718121 is an equidigital number, since it uses as much as digits as its factorization.

66718121 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4032, while the sum is 32.

The square root of 66718121 is about 8168.1161230727. The cubic root of 66718121 is about 405.5844247611.

Adding to 66718121 its reverse (12181766), we get a palindrome (78899887).

The spelling of 66718121 in words is "sixty-six million, seven hundred eighteen thousand, one hundred twenty-one".