66981924 has 48 divisors (see below), whose sum is σ = 174361600. Its totient is φ = 22236768.

The previous prime is 66981919. The next prime is 66981931. The reversal of 66981924 is 42918966.

It is a happy number.

It is a Smith number, since the sum of its digits (45) coincides with the sum of the digits of its prime factors.

It is a self number, because there is not a number n which added to its sum of digits gives 66981924.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 28797 + ... + 31035.

Almost surely, 2^66981924 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 66981924, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (87180800).

66981924 is an abundant number, since it is smaller than the sum of its proper divisors (107379676).

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

66981924 is a wasteful number, since it uses less digits than its factorization.

66981924 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2529 (or 2521 counting only the distinct ones).

The product of its digits is 186624, while the sum is 45.

The square root of 66981924 is about 8184.2485299507. The cubic root of 66981924 is about 406.1182811158.

The spelling of 66981924 in words is "sixty-six million, nine hundred eighty-one thousand, nine hundred twenty-four".