66481861 has 2 divisors, whose sum is σ = 66481862. Its totient is φ = 66481860.

The previous prime is 66481841. The next prime is 66481871. The reversal of 66481861 is 16818466.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 53012961 + 13468900 = 7281^2 + 3670^2 .

It is a cyclic number.

It is not a de Polignac number, because 66481861 - 2⁷ = 66481733 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66481841) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33240930 + 33240931.

It is an arithmetic number, because the mean of its divisors is an integer number (33240931).

Almost surely, 2^66481861 is an apocalyptic number.

It is an amenable number.

66481861 is a deficient number, since it is larger than the sum of its proper divisors (1).

66481861 is an equidigital number, since it uses as much as digits as its factorization.

66481861 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 55296, while the sum is 40.

The square root of 66481861 is about 8153.6409658508. The cubic root of 66481861 is about 405.1051111621.

The spelling of 66481861 in words is "sixty-six million, four hundred eighty-one thousand, eight hundred sixty-one".