66446820 has 144 divisors (see below), whose sum is σ = 226070208. Its totient is φ = 15655680.

The previous prime is 66446797. The next prime is 66446867. The reversal of 66446820 is 2864466.

It is a happy number.

66446820 is a `hidden beast` number, since 6 + 644 + 6 + 8 + 2 + 0 = 666.

It is a super-2 number, since 2×66446820² = 8830359776224800, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36).

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 47 ways as a sum of consecutive naturals, for example, 72807 + ... + 73713.

It is an arithmetic number, because the mean of its divisors is an integer number (1569932).

Almost surely, 2^66446820 is an apocalyptic number.

66446820 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 66446820, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (113035104).

66446820 is an abundant number, since it is smaller than the sum of its proper divisors (159623388).

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

66446820 is a wasteful number, since it uses less digits than its factorization.

66446820 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 970 (or 965 counting only the distinct ones).

The product of its (nonzero) digits is 55296, while the sum is 36.

The square root of 66446820 is about 8151.4918879920. The cubic root of 66446820 is about 405.0339249131.

The spelling of 66446820 in words is "sixty-six million, four hundred forty-six thousand, eight hundred twenty".