66320646 has 64 divisors (see below), whose sum is σ = 155947008. Its totient is φ = 18413568.

The previous prime is 66320627. The next prime is 66320647. The reversal of 66320646 is 64602366.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66320647) 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, 297291 + ... + 297513.

It is an arithmetic number, because the mean of its divisors is an integer number (2436672).

Almost surely, 2^66320646 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 66320646, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (77973504).

66320646 is an abundant number, since it is smaller than the sum of its proper divisors (89626362).

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

66320646 is a wasteful number, since it uses less digits than its factorization.

66320646 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 405.

The product of its (nonzero) digits is 31104, while the sum is 33.

The square root of 66320646 is about 8143.7488910206. The cubic root of 66320646 is about 404.7773932901. Note that the first 3 decimals are identical.

It can be divided in two parts, 66320 and 646, that added together give a palindrome (66966).

The spelling of 66320646 in words is "sixty-six million, three hundred twenty thousand, six hundred forty-six".