66981216 has 48 divisors (see below), whose sum is σ = 177663024. Its totient is φ = 22093824.

The previous prime is 66981199. The next prime is 66981253. The reversal of 66981216 is 61218966.

It is a tau number, because it is divible by the number of its divisors (48).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5716 + ... + 12908.

It is an arithmetic number, because the mean of its divisors is an integer number (3701313).

Almost surely, 2^66981216 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 66981216, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (88831512).

66981216 is an abundant number, since it is smaller than the sum of its proper divisors (110681808).

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

66981216 is a wasteful number, since it uses less digits than its factorization.

66981216 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7303 (or 7295 counting only the distinct ones).

The product of its digits is 31104, while the sum is 39.

The square root of 66981216 is about 8184.2052760179. The cubic root of 66981216 is about 406.1168502185.

The spelling of 66981216 in words is "sixty-six million, nine hundred eighty-one thousand, two hundred sixteen".