666638336 has 192 divisors, whose sum is σ = 1696968000. Its totient is φ = 260112384.

The previous prime is 666638333. The next prime is 666638339. The reversal of 666638336 is 633836666.

It is an interprime number because it is at equal distance from previous prime (666638333) and next prime (666638339).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (666638333) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 9131996 + ... + 9132068.

It is an arithmetic number, because the mean of its divisors is an integer number (8838375).

Almost surely, 2^666638336 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 666638336, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (848484000).

666638336 is an abundant number, since it is smaller than the sum of its proper divisors (1030329664).

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

666638336 is an equidigital number, since it uses as much as digits as its factorization.

666638336 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 129 (or 95 counting only the distinct ones).

The product of its digits is 1679616, while the sum is 47.

The square root of 666638336 is about 25819.3403478865. The cubic root of 666638336 is about 873.5680900025.

The spelling of 666638336 in words is "six hundred sixty-six million, six hundred thirty-eight thousand, three hundred thirty-six".