66721312 has 96 divisors (see below), whose sum is σ = 161239680. Its totient is φ = 26542080.

The previous prime is 66721301. The next prime is 66721349. The reversal of 66721312 is 21312766.

It is a Harshad number since it is a multiple of its sum of digits (28).

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, 259488 + ... + 259744.

It is an arithmetic number, because the mean of its divisors is an integer number (1679580).

Almost surely, 2^66721312 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 66721312, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (80619840).

66721312 is an abundant number, since it is smaller than the sum of its proper divisors (94518368).

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

66721312 is a wasteful number, since it uses less digits than its factorization.

66721312 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 354 (or 346 counting only the distinct ones).

The product of its digits is 3024, while the sum is 28.

The square root of 66721312 is about 8168.3114534156. The cubic root of 66721312 is about 405.5908907669.

The spelling of 66721312 in words is "sixty-six million, seven hundred twenty-one thousand, three hundred twelve".