66401557177 has 2 divisors, whose sum is σ = 66401557178. Its totient is φ = 66401557176.

The previous prime is 66401557147. The next prime is 66401557193. The reversal of 66401557177 is 77175510466.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 62158467856 + 4243089321 = 249316^2 + 65139^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66401557177 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 66401557177.

It is not a weakly prime, because it can be changed into another prime (66401557127) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33200778588 + 33200778589.

It is an arithmetic number, because the mean of its divisors is an integer number (33200778589).

Almost surely, 2^66401557177 is an apocalyptic number.

It is an amenable number.

66401557177 is a deficient number, since it is larger than the sum of its proper divisors (1).

66401557177 is an equidigital number, since it uses as much as digits as its factorization.

66401557177 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1234800, while the sum is 49.

The spelling of 66401557177 in words is "sixty-six billion, four hundred one million, five hundred fifty-seven thousand, one hundred seventy-seven".