161666817840 has 800 divisors, whose sum is σ = 659995471872. Its totient is φ = 36267264000.

The previous prime is 161666817779. The next prime is 161666817857. The reversal of 161666817840 is 48718666161.

161666817840 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a super-2 number, since 2×161666817840² (a number of 23 digits) contains 22 as substring.

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

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 159 ways as a sum of consecutive naturals, for example, 50821050 + ... + 50824230.

Almost surely, 2^161666817840 is an apocalyptic number.

161666817840 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 161666817840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (329997735936).

161666817840 is an abundant number, since it is smaller than the sum of its proper divisors (498328654032).

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

161666817840 is a wasteful number, since it uses less digits than its factorization.

161666817840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3271 (or 3256 counting only the distinct ones).

The product of its (nonzero) digits is 2322432, while the sum is 54.

The spelling of 161666817840 in words is "one hundred sixty-one billion, six hundred sixty-six million, eight hundred seventeen thousand, eight hundred forty".