66540277381 has 2 divisors, whose sum is σ = 66540277382. Its totient is φ = 66540277380.

The previous prime is 66540277291. The next prime is 66540277403. The reversal of 66540277381 is 18377204566.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 62765280900 + 3774996481 = 250530^2 + 61441^2 .

It is a cyclic number.

It is not a de Polignac number, because 66540277381 - 2⁷ = 66540277253 is a prime.

It is a super-2 number, since 2×66540277381² (a number of 22 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66540277981) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33270138690 + 33270138691.

It is an arithmetic number, because the mean of its divisors is an integer number (33270138691).

Almost surely, 2^66540277381 is an apocalyptic number.

It is an amenable number.

66540277381 is a deficient number, since it is larger than the sum of its proper divisors (1).

66540277381 is an equidigital number, since it uses as much as digits as its factorization.

66540277381 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1693440, while the sum is 49.

The spelling of 66540277381 in words is "sixty-six billion, five hundred forty million, two hundred seventy-seven thousand, three hundred eighty-one".