66721256 has 64 divisors (see below), whose sum is σ = 147329280. Its totient is φ = 27740160.

The previous prime is 66721177. The next prime is 66721261. The reversal of 66721256 is 65212766.

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, 385586 + ... + 385758.

It is an arithmetic number, because the mean of its divisors is an integer number (2302020).

Almost surely, 2^66721256 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 66721256, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (73664640).

66721256 is an abundant number, since it is smaller than the sum of its proper divisors (80608024).

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

66721256 is a wasteful number, since it uses less digits than its factorization.

66721256 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 354 (or 350 counting only the distinct ones).

The product of its digits is 30240, while the sum is 35.

The square root of 66721256 is about 8168.3080255338. The cubic root of 66721256 is about 405.5907772945.

The spelling of 66721256 in words is "sixty-six million, seven hundred twenty-one thousand, two hundred fifty-six".