666217020 has 96 divisors (see below), whose sum is σ = 2135282688. Its totient is φ = 152036352.

The previous prime is 666216997. The next prime is 666217021. The reversal of 666217020 is 20712666.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (666217021) by changing a digit.

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 31 ways as a sum of consecutive naturals, for example, 513012 + ... + 514308.

It is an arithmetic number, because the mean of its divisors is an integer number (22242528).

Almost surely, 2^666217020 is an apocalyptic number.

666217020 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 666217020, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1067641344).

666217020 is an abundant number, since it is smaller than the sum of its proper divisors (1469065668).

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

666217020 is a wasteful number, since it uses less digits than its factorization.

666217020 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2539 (or 2537 counting only the distinct ones).

The product of its (nonzero) digits is 6048, while the sum is 30.

The square root of 666217020 is about 25811.1801357474. The cubic root of 666217020 is about 873.3840192921.

Adding to 666217020 its reverse (20712666), we get a palindrome (686929686).

The spelling of 666217020 in words is "six hundred sixty-six million, two hundred seventeen thousand, twenty".