666985956 has 384 divisors, whose sum is σ = 2239856640. Its totient is φ = 149299200.

The previous prime is 666985951. The next prime is 666985961. The reversal of 666985956 is 659589666.

666985956 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an interprime number because it is at equal distance from previous prime (666985951) and next prime (666985961).

It is a self number, because there is not a number n which added to its sum of digits gives 666985956.

It is not an unprimeable number, because it can be changed into a prime (666985951) by changing a digit.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 10934166 + ... + 10934226.

It is an arithmetic number, because the mean of its divisors is an integer number (5832960).

Almost surely, 2^666985956 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 666985956, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1119928320).

666985956 is an abundant number, since it is smaller than the sum of its proper divisors (1572870684).

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

666985956 is a wasteful number, since it uses less digits than its factorization.

666985956 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 155 (or 153 counting only the distinct ones).

The product of its digits is 20995200, while the sum is 60.

The square root of 666985956 is about 25826.0712459329. The cubic root of 666985956 is about 873.7199049399.

The spelling of 666985956 in words is "six hundred sixty-six million, nine hundred eighty-five thousand, nine hundred fifty-six".