1664917585920 has 360 divisors, whose sum is σ = 5782873247424. Its totient is φ = 443106459648.

The previous prime is 1664917585879. The next prime is 1664917585951. The reversal of 1664917585920 is 295857194661.

1664917585920 is a `hidden beast` number, since 1 + 6 + 6 + 49 + 1 + 7 + 585 + 9 + 2 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (360).

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, 432781437 + ... + 432785283.

Almost surely, 2^{1664917585920} is an apocalyptic number.

1664917585920 is a gapful number since it is divisible by the number (10) 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 1664917585920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2891436623712).

1664917585920 is an abundant number, since it is smaller than the sum of its proper divisors (4117955661504).

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

1664917585920 is an equidigital number, since it uses as much as digits as its factorization.

1664917585920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4473 (or 4444 counting only the distinct ones).

The product of its (nonzero) digits is 32659200, while the sum is 63.

The spelling of 1664917585920 in words is "one trillion, six hundred sixty-four billion, nine hundred seventeen million, five hundred eighty-five thousand, nine hundred twenty".