66188557381 has 2 divisors, whose sum is σ = 66188557382. Its totient is φ = 66188557380.

The previous prime is 66188557321. The next prime is 66188557451. The reversal of 66188557381 is 18375588166.

66188557381 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 33880292356 + 32308265025 = 184066^2 + 179745^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66188557381 is a prime.

It is a super-2 number, since 2×66188557381² (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 (66188557321) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33094278690 + 33094278691.

It is an arithmetic number, because the mean of its divisors is an integer number (33094278691).

Almost surely, 2^66188557381 is an apocalyptic number.

It is an amenable number.

66188557381 is a deficient number, since it is larger than the sum of its proper divisors (1).

66188557381 is an equidigital number, since it uses as much as digits as its factorization.

66188557381 is an evil number, because the sum of its binary digits is even.

The product of its digits is 9676800, while the sum is 58.

The spelling of 66188557381 in words is "sixty-six billion, one hundred eighty-eight million, five hundred fifty-seven thousand, three hundred eighty-one".