665943966450 has 288 divisors, whose sum is σ = 2193625848960. Its totient is φ = 146966400000.

The previous prime is 665943966437. The next prime is 665943966451. The reversal of 665943966450 is 54669349566.

It is a happy number.

665943966450 is a `hidden beast` number, since 6 + 6 + 5 + 94 + 3 + 96 + 6 + 450 = 666.

It is a Harshad number since it is a multiple of its sum of digits (63).

It is not an unprimeable number, because it can be changed into a prime (665943966451) 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 143 ways as a sum of consecutive naturals, for example, 2331450 + ... + 2601450.

It is an arithmetic number, because the mean of its divisors is an integer number (7616756420).

Almost surely, 2^665943966450 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 665943966450, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1096812924480).

665943966450 is an abundant number, since it is smaller than the sum of its proper divisors (1527681882510).

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

665943966450 is a wasteful number, since it uses less digits than its factorization.

665943966450 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 270064 (or 270047 counting only the distinct ones).

The product of its (nonzero) digits is 125971200, while the sum is 63.

The spelling of 665943966450 in words is "six hundred sixty-five billion, nine hundred forty-three million, nine hundred sixty-six thousand, four hundred fifty".