66165557 has 2 divisors, whose sum is σ = 66165558. Its totient is φ = 66165556.

The previous prime is 66165527. The next prime is 66165601. The reversal of 66165557 is 75556166.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 61999876 + 4165681 = 7874^2 + 2041^2 .

It is a cyclic number.

It is not a de Polignac number, because 66165557 - 2⁶ = 66165493 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66165527) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33082778 + 33082779.

It is an arithmetic number, because the mean of its divisors is an integer number (33082779).

Almost surely, 2^66165557 is an apocalyptic number.

It is an amenable number.

66165557 is a deficient number, since it is larger than the sum of its proper divisors (1).

66165557 is an equidigital number, since it uses as much as digits as its factorization.

66165557 is an evil number, because the sum of its binary digits is even.

The product of its digits is 189000, while the sum is 41.

The square root of 66165557 is about 8134.2213517951. The cubic root of 66165557 is about 404.4616267713.

The spelling of 66165557 in words is "sixty-six million, one hundred sixty-five thousand, five hundred fifty-seven".