66398446421 has 2 divisors, whose sum is σ = 66398446422. Its totient is φ = 66398446420.

The previous prime is 66398446399. The next prime is 66398446453. The reversal of 66398446421 is 12464489366.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 50528745796 + 15869700625 = 224786^2 + 125975^2 .

It is a cyclic number.

It is not a de Polignac number, because 66398446421 - 2²⁶ = 66331337557 is a prime.

It is a super-3 number, since 3×66398446421³ (a number of 33 digits) contains 333 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66398446921) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33199223210 + 33199223211.

It is an arithmetic number, because the mean of its divisors is an integer number (33199223211).

Almost surely, 2^66398446421 is an apocalyptic number.

It is an amenable number.

66398446421 is a deficient number, since it is larger than the sum of its proper divisors (1).

66398446421 is an equidigital number, since it uses as much as digits as its factorization.

66398446421 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 5971968, while the sum is 53.

The spelling of 66398446421 in words is "sixty-six billion, three hundred ninety-eight million, four hundred forty-six thousand, four hundred twenty-one".