66811556 has 12 divisors (see below), whose sum is σ = 133623168. Its totient is φ = 28633512.

The previous prime is 66811517. The next prime is 66811567. The reversal of 66811556 is 65511866.

66811556 is an admirable number.

It is a super-2 number, since 2×66811556² = 8927568030282272, which contains 22 as substring.

It is a hoax number, since the sum of its digits (38) coincides with the sum of the digits of its distinct prime factors.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1193036 + ... + 1193091.

It is an arithmetic number, because the mean of its divisors is an integer number (11135264).

Almost surely, 2^66811556 is an apocalyptic number.

It is an amenable number.

66811556 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

66811556 is a wasteful number, since it uses less digits than its factorization.

66811556 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2386138 (or 2386136 counting only the distinct ones).

The product of its digits is 43200, while the sum is 38.

The square root of 66811556 is about 8173.8336170979. The cubic root of 66811556 is about 405.7736692203.

The spelling of 66811556 in words is "sixty-six million, eight hundred eleven thousand, five hundred fifty-six".