66331557 has 12 divisors (see below), whose sum is σ = 95902560. Its totient is φ = 44179368.

The previous prime is 66331549. The next prime is 66331561. The reversal of 66331557 is 75513366.

It is a happy number.

66331557 is a `hidden beast` number, since 6 + 633 + 15 + 5 + 7 = 666.

It is not a de Polignac number, because 66331557 - 2³ = 66331549 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66330557) 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, 8944 + ... + 14582.

It is an arithmetic number, because the mean of its divisors is an integer number (7991880).

Almost surely, 2^66331557 is an apocalyptic number.

It is an amenable number.

66331557 is a deficient number, since it is larger than the sum of its proper divisors (29571003).

66331557 is a wasteful number, since it uses less digits than its factorization.

66331557 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6952 (or 6949 counting only the distinct ones).

The product of its digits is 56700, while the sum is 36.

The square root of 66331557 is about 8144.4187637916. The cubic root of 66331557 is about 404.7995899173.

The spelling of 66331557 in words is "sixty-six million, three hundred thirty-one thousand, five hundred fifty-seven".