1668494640 has 40 divisors (see below), whose sum is σ = 5172334128. Its totient is φ = 444931840.

The previous prime is 1668494627. The next prime is 1668494647. The reversal of 1668494640 is 464948661.

It is a happy number.

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

It is a Harshad number since it is a multiple of its sum of digits (48).

It is a self number, because there is not a number n which added to its sum of digits gives 1668494640.

It is not an unprimeable number, because it can be changed into a prime (1668494647) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3475791 + ... + 3476270.

Almost surely, 2^1668494640 is an apocalyptic number.

1668494640 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1668494640 is an abundant number, since it is smaller than the sum of its proper divisors (3503839488).

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

1668494640 is a wasteful number, since it uses less digits than its factorization.

1668494640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6952077 (or 6952071 counting only the distinct ones).

The product of its (nonzero) digits is 995328, while the sum is 48.

The square root of 1668494640 is about 40847.2109206981. The cubic root of 1668494640 is about 1186.0644035297.

The spelling of 1668494640 in words is "one billion, six hundred sixty-eight million, four hundred ninety-four thousand, six hundred forty".