66425783821 has 2 divisors, whose sum is σ = 66425783822. Its totient is φ = 66425783820.

The previous prime is 66425783797. The next prime is 66425783839. The reversal of 66425783821 is 12838752466.

66425783821 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 63207490921 + 3218292900 = 251411^2 + 56730^2 .

It is a cyclic number.

It is not a de Polignac number, because 66425783821 - 2⁷ = 66425783693 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66425786821) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33212891910 + 33212891911.

It is an arithmetic number, because the mean of its divisors is an integer number (33212891911).

Almost surely, 2^66425783821 is an apocalyptic number.

It is an amenable number.

66425783821 is a deficient number, since it is larger than the sum of its proper divisors (1).

66425783821 is an equidigital number, since it uses as much as digits as its factorization.

66425783821 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3870720, while the sum is 52.

The spelling of 66425783821 in words is "sixty-six billion, four hundred twenty-five million, seven hundred eighty-three thousand, eight hundred twenty-one".