66654001681 has 2 divisors, whose sum is σ = 66654001682. Its totient is φ = 66654001680.

The previous prime is 66654001651. The next prime is 66654001699. The reversal of 66654001681 is 18610045666.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 52056529281 + 14597472400 = 228159^2 + 120820^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66654001681 is a prime.

It is a super-2 number, since 2×66654001681² (a number of 22 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (66654001651) 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, 33327000840 + 33327000841.

It is an arithmetic number, because the mean of its divisors is an integer number (33327000841).

Almost surely, 2^66654001681 is an apocalyptic number.

It is an amenable number.

66654001681 is a deficient number, since it is larger than the sum of its proper divisors (1).

66654001681 is an equidigital number, since it uses as much as digits as its factorization.

66654001681 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 207360, while the sum is 43.

The spelling of 66654001681 in words is "sixty-six billion, six hundred fifty-four million, one thousand, six hundred eighty-one".