668194640 has 40 divisors (see below), whose sum is σ = 1573232640. Its totient is φ = 263892096.

The previous prime is 668194627. The next prime is 668194661. The reversal of 668194640 is 46491866.

It is a tau number, because it is divible by the number of its divisors (40).

It is a junction number, because it is equal to n+sod(n) for n = 668194591 and 668194600.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 46544 + ... + 59183.

It is an arithmetic number, because the mean of its divisors is an integer number (39330816).

Almost surely, 2^668194640 is an apocalyptic number.

It is an amenable number.

668194640 is an abundant number, since it is smaller than the sum of its proper divisors (905038000).

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

668194640 is a wasteful number, since it uses less digits than its factorization.

668194640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 105819 (or 105813 counting only the distinct ones).

The product of its (nonzero) digits is 248832, while the sum is 44.

The square root of 668194640 is about 25849.4611162399. The cubic root of 668194640 is about 874.2473593242.

The spelling of 668194640 in words is "six hundred sixty-eight million, one hundred ninety-four thousand, six hundred forty".