668206440 has 384 divisors, whose sum is σ = 2547417600. Its totient is φ = 150197760.

The previous prime is 668206417. The next prime is 668206493. The reversal of 668206440 is 44602866.

It is a happy number.

668206440 is a `hidden beast` number, since 6 + 6 + 8 + 2 + 0 + 644 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 668206395 and 668206404.

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 95 ways as a sum of consecutive naturals, for example, 6244867 + ... + 6244973.

It is an arithmetic number, because the mean of its divisors is an integer number (6633900).

Almost surely, 2^668206440 is an apocalyptic number.

668206440 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 668206440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1273708800).

668206440 is an abundant number, since it is smaller than the sum of its proper divisors (1879211160).

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

668206440 is a wasteful number, since it uses less digits than its factorization.

668206440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 237 (or 230 counting only the distinct ones).

The product of its (nonzero) digits is 55296, while the sum is 36.

The square root of 668206440 is about 25849.6893598356. The cubic root of 668206440 is about 874.2525055583.

The spelling of 668206440 in words is "six hundred sixty-eight million, two hundred six thousand, four hundred forty".