166811385899520 has 560 divisors, whose sum is σ = 600106194207432. Its totient is φ = 44449955020800.

The previous prime is 166811385899461. The next prime is 166811385899573. The reversal of 166811385899520 is 25998583118661.

166811385899520 is a `hidden beast` number, since 1 + 6 + 6 + 8 + 1 + 1 + 3 + 8 + 5 + 8 + 99 + 520 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 166074562808064 + 736823091456 = 12886992^2 + 858384^2 .

It is a Harshad number since it is a multiple of its sum of digits (72).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 55 ways as a sum of consecutive naturals, for example, 2562314970 + ... + 2562380070.

Almost surely, 2^{166811385899520} is an apocalyptic number.

166811385899520 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 166811385899520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (300053097103716).

166811385899520 is an abundant number, since it is smaller than the sum of its proper divisors (433294808307912).

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

166811385899520 is an frugal number, since it uses more digits than its factorization.

166811385899520 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 66515 (or 66484 counting only the distinct ones).

The product of its (nonzero) digits is 223948800, while the sum is 72.

The spelling of 166811385899520 in words is "one hundred sixty-six trillion, eight hundred eleven billion, three hundred eighty-five million, eight hundred ninety-nine thousand, five hundred twenty".