66345557 has 2 divisors, whose sum is σ = 66345558. Its totient is φ = 66345556.

The previous prime is 66345553. The next prime is 66345571. The reversal of 66345557 is 75554366.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 39450961 + 26894596 = 6281^2 + 5186^2 .

It is a cyclic number.

It is not a de Polignac number, because 66345557 - 2² = 66345553 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66345553) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33172778 + 33172779.

It is an arithmetic number, because the mean of its divisors is an integer number (33172779).

Almost surely, 2^66345557 is an apocalyptic number.

It is an amenable number.

66345557 is a deficient number, since it is larger than the sum of its proper divisors (1).

66345557 is an equidigital number, since it uses as much as digits as its factorization.

66345557 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 378000, while the sum is 41.

The square root of 66345557 is about 8145.2782027381. The cubic root of 66345557 is about 404.8280670397.

The spelling of 66345557 in words is "sixty-six million, three hundred forty-five thousand, five hundred fifty-seven".