666947646 has 12 divisors (see below), whose sum is σ = 1445053272. Its totient is φ = 222315876.

The previous prime is 666947641. The next prime is 666947651. The reversal of 666947646 is 646749666.

It is an interprime number because it is at equal distance from previous prime (666947641) and next prime (666947651).

It is a junction number, because it is equal to n+sod(n) for n = 666947592 and 666947601.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (666947641) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 18526306 + ... + 18526341.

It is an arithmetic number, because the mean of its divisors is an integer number (120421106).

Almost surely, 2^666947646 is an apocalyptic number.

666947646 is an abundant number, since it is smaller than the sum of its proper divisors (778105626).

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

666947646 is a wasteful number, since it uses less digits than its factorization.

666947646 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 37052655 (or 37052652 counting only the distinct ones).

The product of its digits is 7838208, while the sum is 54.

The square root of 666947646 is about 25825.3295429119. The cubic root of 666947646 is about 873.7031765265.

The spelling of 666947646 in words is "six hundred sixty-six million, nine hundred forty-seven thousand, six hundred forty-six".