66605220 has 96 divisors (see below), whose sum is σ = 226074240. Its totient is φ = 16145280.

The previous prime is 66605219. The next prime is 66605221. The reversal of 66605220 is 2250666.

It is an interprime number because it is at equal distance from previous prime (66605219) and next prime (66605221).

It is a Harshad number since it is a multiple of its sum of digits (27).

It is not an unprimeable number, because it can be changed into a prime (66605221) 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, 334 + ... + 11546.

It is an arithmetic number, because the mean of its divisors is an integer number (2354940).

Almost surely, 2^66605220 is an apocalyptic number.

66605220 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 66605220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (113037120).

66605220 is an abundant number, since it is smaller than the sum of its proper divisors (159469020).

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

66605220 is a wasteful number, since it uses less digits than its factorization.

66605220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11242 (or 11234 counting only the distinct ones).

The product of its (nonzero) digits is 4320, while the sum is 27.

The square root of 66605220 is about 8161.2021173354. The cubic root of 66605220 is about 405.3555177315.

Adding to 66605220 its reverse (2250666), we get a palindrome (68855886).

The spelling of 66605220 in words is "sixty-six million, six hundred five thousand, two hundred twenty".