66821328 has 160 divisors (see below), whose sum is σ = 230937600. Its totient is φ = 18071424.

The previous prime is 66821327. The next prime is 66821329. The reversal of 66821328 is 82312866.

It is an interprime number because it is at equal distance from previous prime (66821327) and next prime (66821329).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a nude number because it is divisible by every one of its digits.

It is a junction number, because it is equal to n+sod(n) for n = 66821292 and 66821301.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66821323) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 56875 + ... + 58037.

It is an arithmetic number, because the mean of its divisors is an integer number (1443360).

Almost surely, 2^66821328 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 66821328, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (115468800).

66821328 is an abundant number, since it is smaller than the sum of its proper divisors (164116272).

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

66821328 is a wasteful number, since it uses less digits than its factorization.

66821328 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1206 (or 1194 counting only the distinct ones).

The product of its digits is 27648, while the sum is 36.

The square root of 66821328 is about 8174.4313563697. The cubic root of 66821328 is about 405.7934513619.

The spelling of 66821328 in words is "sixty-six million, eight hundred twenty-one thousand, three hundred twenty-eight".