66655557 has 12 divisors (see below), whose sum is σ = 97441344. Its totient is φ = 43901160.

The previous prime is 66655513. The next prime is 66655573. The reversal of 66655557 is 75555666.

It is not a de Polignac number, because 66655557 - 2⁷ = 66655429 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66655507) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 43869 + ... + 45362.

It is an arithmetic number, because the mean of its divisors is an integer number (8120112).

Almost surely, 2^66655557 is an apocalyptic number.

It is an amenable number.

66655557 is a deficient number, since it is larger than the sum of its proper divisors (30785787).

66655557 is a wasteful number, since it uses less digits than its factorization.

66655557 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 89320 (or 89317 counting only the distinct ones).

The product of its digits is 945000, while the sum is 45.

The square root of 66655557 is about 8164.2854555680. The cubic root of 66655557 is about 405.4576080414.

The spelling of 66655557 in words is "sixty-six million, six hundred fifty-five thousand, five hundred fifty-seven".