66042071681 has 2 divisors, whose sum is σ = 66042071682. Its totient is φ = 66042071680.

The previous prime is 66042071677. The next prime is 66042071707. The reversal of 66042071681 is 18617024066.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 66041290225 + 781456 = 256985^2 + 884^2 .

It is a cyclic number.

It is not a de Polignac number, because 66042071681 - 2² = 66042071677 is a prime.

It is a super-2 number, since 2×66042071681² (a number of 22 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (66042071611) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33021035840 + 33021035841.

It is an arithmetic number, because the mean of its divisors is an integer number (33021035841).

Almost surely, 2^66042071681 is an apocalyptic number.

It is an amenable number.

66042071681 is a deficient number, since it is larger than the sum of its proper divisors (1).

66042071681 is an equidigital number, since it uses as much as digits as its factorization.

66042071681 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 96768, while the sum is 41.

The spelling of 66042071681 in words is "sixty-six billion, forty-two million, seventy-one thousand, six hundred eighty-one".