66540220 has 12 divisors (see below), whose sum is σ = 139734504. Its totient is φ = 26616080.

The previous prime is 66540209. The next prime is 66540233. The reversal of 66540220 is 2204566.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1663486 + ... + 1663525.

It is an arithmetic number, because the mean of its divisors is an integer number (11644542).

Almost surely, 2^66540220 is an apocalyptic number.

It is an amenable number.

66540220 is an abundant number, since it is smaller than the sum of its proper divisors (73194284).

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

66540220 is a wasteful number, since it uses less digits than its factorization.

66540220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3327020 (or 3327018 counting only the distinct ones).

The product of its (nonzero) digits is 2880, while the sum is 25.

The square root of 66540220 is about 8157.2188888125. The cubic root of 66540220 is about 405.2236127330.

Adding to 66540220 its reverse (2204566), we get a palindrome (68744786).

The spelling of 66540220 in words is "sixty-six million, five hundred forty thousand, two hundred twenty".