66855690 has 48 divisors (see below), whose sum is σ = 189629856. Its totient is φ = 16207200.

The previous prime is 66855689. The next prime is 66855727. The reversal of 66855690 is 9655866.

66855690 is a `hidden beast` number, since 6 + 6 + 8 + 556 + 90 = 666.

66855690 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a super-2 number, since 2×66855690² = 8939366570752200, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 32776 + ... + 34755.

It is an arithmetic number, because the mean of its divisors is an integer number (3950622).

Almost surely, 2^66855690 is an apocalyptic number.

66855690 is an abundant number, since it is smaller than the sum of its proper divisors (122774166).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

66855690 is a wasteful number, since it uses less digits than its factorization.

66855690 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 67555 (or 67552 counting only the distinct ones).

The product of its (nonzero) digits is 388800, while the sum is 45.

The square root of 66855690 is about 8176.5328838084. The cubic root of 66855690 is about 405.8629974461.

The spelling of 66855690 in words is "sixty-six million, eight hundred fifty-five thousand, six hundred ninety".