668051640 has 96 divisors (see below), whose sum is σ = 2203652880. Its totient is φ = 175481856.

The previous prime is 668051617. The next prime is 668051651. The reversal of 668051640 is 46150866.

668051640 is a `hidden beast` number, since 6 + 6 + 8 + 0 + 5 + 1 + 640 = 666.

668051640 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 = 668051595 and 668051604.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 10272 + ... + 37968.

Almost surely, 2^668051640 is an apocalyptic number.

668051640 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 668051640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1101826440).

668051640 is an abundant number, since it is smaller than the sum of its proper divisors (1535601240).

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

668051640 is a wasteful number, since it uses less digits than its factorization.

668051640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27781 (or 27774 counting only the distinct ones).

The product of its (nonzero) digits is 34560, while the sum is 36.

The square root of 668051640 is about 25846.6949531270. The cubic root of 668051640 is about 874.1849891284.

The spelling of 668051640 in words is "six hundred sixty-eight million, fifty-one thousand, six hundred forty".