66981824 has 168 divisors, whose sum is σ = 175125888. Its totient is φ = 25159680.

The previous prime is 66981787. The next prime is 66981833. The reversal of 66981824 is 42818966.

It is a happy number.

It is a zygodrome in base 2.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1263782 + ... + 1263834.

It is an arithmetic number, because the mean of its divisors is an integer number (1042416).

Almost surely, 2^66981824 is an apocalyptic number.

66981824 is a gapful number since it is divisible by the number (64) 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 66981824, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (87562944).

66981824 is an abundant number, since it is smaller than the sum of its proper divisors (108144064).

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

66981824 is a wasteful number, since it uses less digits than its factorization.

66981824 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 123 (or 106 counting only the distinct ones).

The product of its digits is 165888, while the sum is 44.

The square root of 66981824 is about 8184.2424206520. The cubic root of 66981824 is about 406.1180790123.

The spelling of 66981824 in words is "sixty-six million, nine hundred eighty-one thousand, eight hundred twenty-four".