666649760 has 96 divisors (see below), whose sum is σ = 1804747392. Its totient is φ = 227957760.

The previous prime is 666649667. The next prime is 666649771. The reversal of 666649760 is 67946666.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 666649699 and 666649708.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 686075 + ... + 687045.

It is an arithmetic number, because the mean of its divisors is an integer number (18799452).

Almost surely, 2^666649760 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 666649760, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (902373696).

666649760 is an abundant number, since it is smaller than the sum of its proper divisors (1138097632).

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

666649760 is a wasteful number, since it uses less digits than its factorization.

666649760 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1606 (or 1598 counting only the distinct ones).

The product of its (nonzero) digits is 1959552, while the sum is 50.

The square root of 666649760 is about 25819.5615764482. The cubic root of 666649760 is about 873.5730800070.

The spelling of 666649760 in words is "six hundred sixty-six million, six hundred forty-nine thousand, seven hundred sixty".