66543220 has 24 divisors (see below), whose sum is σ = 139908384. Its totient is φ = 26585376.

The previous prime is 66543203. The next prime is 66543221. The reversal of 66543220 is 2234566.

It is a happy number.

It is a nialpdrome in base 10.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66543221) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 22339 + ... + 25141.

It is an arithmetic number, because the mean of its divisors is an integer number (5829516).

Almost surely, 2^66543220 is an apocalyptic number.

It is an amenable number.

66543220 is an abundant number, since it is smaller than the sum of its proper divisors (73365164).

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

66543220 is a wasteful number, since it uses less digits than its factorization.

66543220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3999 (or 3997 counting only the distinct ones).

The product of its (nonzero) digits is 8640, while the sum is 28.

The square root of 66543220 is about 8157.4027729419. The cubic root of 66543220 is about 405.2297025464.

Adding to 66543220 its reverse (2234566), we get a palindrome (68777786).

The spelling of 66543220 in words is "sixty-six million, five hundred forty-three thousand, two hundred twenty".