66646866 has 64 divisors (see below), whose sum is σ = 157852800. Its totient is φ = 18493440.

The previous prime is 66646829. The next prime is 66646897. The reversal of 66646866 is 66864666.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 148210 + ... + 148658.

It is an arithmetic number, because the mean of its divisors is an integer number (2466450).

Almost surely, 2^66646866 is an apocalyptic number.

66646866 is a gapful number since it is divisible by the number (66) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 66646866, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (78926400).

66646866 is an abundant number, since it is smaller than the sum of its proper divisors (91205934).

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

66646866 is a wasteful number, since it uses less digits than its factorization.

66646866 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 651.

The product of its digits is 1492992, while the sum is 48.

The square root of 66646866 is about 8163.7531809824. The cubic root of 66646866 is about 405.4399851784.

It can be divided in two parts, 6664 and 6866, that added together give a triangular number (13530 = T₁₆₄).

The spelling of 66646866 in words is "sixty-six million, six hundred forty-six thousand, eight hundred sixty-six".