165994323840 has 640 divisors, whose sum is σ = 629382758400. Its totient is φ = 41573855232.

The previous prime is 165994323791. The next prime is 165994323853. The reversal of 165994323840 is 48323499561.

165994323840 is a `hidden beast` number, since 1 + 6 + 599 + 4 + 3 + 2 + 3 + 8 + 40 = 666.

It is a tau number, because it is divible by the number of its divisors (640).

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 125089257 + ... + 125090583.

It is an arithmetic number, because the mean of its divisors is an integer number (983410560).

Almost surely, 2^165994323840 is an apocalyptic number.

165994323840 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 165994323840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (314691379200).

165994323840 is an abundant number, since it is smaller than the sum of its proper divisors (463388434560).

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

165994323840 is a wasteful number, since it uses less digits than its factorization.

165994323840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1504 (or 1483 counting only the distinct ones).

The product of its (nonzero) digits is 5598720, while the sum is 54.

The spelling of 165994323840 in words is "one hundred sixty-five billion, nine hundred ninety-four million, three hundred twenty-three thousand, eight hundred forty".