646662666 has 48 divisors (see below), whose sum is σ = 1439357472. Its totient is φ = 192532320.

The previous prime is 646662661. The next prime is 646662671. The reversal of 646662666 is 666266646.

It is an interprime number because it is at equal distance from previous prime (646662661) and next prime (646662671).

It is not an unprimeable number, because it can be changed into a prime (646662661) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 70645 + ... + 79271.

It is an arithmetic number, because the mean of its divisors is an integer number (29986614).

Almost surely, 2^646662666 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 646662666, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (719678736).

646662666 is an abundant number, since it is smaller than the sum of its proper divisors (792694806).

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

646662666 is a wasteful number, since it uses less digits than its factorization.

646662666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8707 (or 8676 counting only the distinct ones).

The product of its digits is 2239488, while the sum is 48.

The square root of 646662666 is about 25429.5628354087. The cubic root of 646662666 is about 864.7540329972.

The spelling of 646662666 in words is "six hundred forty-six million, six hundred sixty-two thousand, six hundred sixty-six".