1664317840 has 40 divisors (see below), whose sum is σ = 3873377088. Its totient is φ = 665066880.

The previous prime is 1664317813. The next prime is 1664317871. The reversal of 1664317840 is 487134661.

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

It is a hoax number, since the sum of its digits (40) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (40).

It is a junction number, because it is equal to n+sod(n) for n = 1664317793 and 1664317802.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 75255 + ... + 94825.

Almost surely, 2^1664317840 is an apocalyptic number.

1664317840 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1664317840 is an abundant number, since it is smaller than the sum of its proper divisors (2209059248).

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

1664317840 is a wasteful number, since it uses less digits than its factorization.

1664317840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20647 (or 20641 counting only the distinct ones).

The product of its (nonzero) digits is 96768, while the sum is 40.

The square root of 1664317840 is about 40796.0517697485. The cubic root of 1664317840 is about 1185.0738712576.

The spelling of 1664317840 in words is "one billion, six hundred sixty-four million, three hundred seventeen thousand, eight hundred forty".