666745650 has 72 divisors (see below), whose sum is σ = 1794857220. Its totient is φ = 177448320.

The previous prime is 666745621. The next prime is 666745657. The reversal of 666745650 is 56547666.

It can be written as a sum of positive squares in 6 ways, for example, as 30041361 + 636704289 = 5481^2 + 25233^2 .

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a junction number, because it is equal to n+sod(n) for n = 666745596 and 666745605.

It is not an unprimeable number, because it can be changed into a prime (666745657) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 292716 + ... + 294984.

Almost surely, 2^666745650 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 666745650, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (897428610).

666745650 is an abundant number, since it is smaller than the sum of its proper divisors (1128111570).

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

666745650 is a wasteful number, since it uses less digits than its factorization.

666745650 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2940 (or 2932 counting only the distinct ones).

The product of its (nonzero) digits is 907200, while the sum is 45.

The square root of 666745650 is about 25821.4184350899. The cubic root of 666745650 is about 873.6149625225.

The spelling of 666745650 in words is "six hundred sixty-six million, seven hundred forty-five thousand, six hundred fifty".