66021861708 has 144 divisors (see below), whose sum is σ = 192922853760. Its totient is φ = 18814809600.

The previous prime is 66021861673. The next prime is 66021861739. The reversal of 66021861708 is 80716812066.

It is a happy number.

66021861708 is a `hidden beast` number, since 6 + 6 + 0 + 21 + 8 + 617 + 0 + 8 = 666.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 10626723 + ... + 10632933.

It is an arithmetic number, because the mean of its divisors is an integer number (1339742040).

Almost surely, 2^66021861708 is an apocalyptic number.

66021861708 is a gapful number since it is divisible by the number (68) 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 66021861708, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (96461426880).

66021861708 is an abundant number, since it is smaller than the sum of its proper divisors (126900992052).

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

66021861708 is a wasteful number, since it uses less digits than its factorization.

66021861708 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7828 (or 7823 counting only the distinct ones).

The product of its (nonzero) digits is 193536, while the sum is 45.

It can be divided in two parts, 66021 and 861708, that added together give a palindrome (927729).

The spelling of 66021861708 in words is "sixty-six billion, twenty-one million, eight hundred sixty-one thousand, seven hundred eight".