166721805900 has 360 divisors, whose sum is σ = 595570516464. Its totient is φ = 40083724800.

The previous prime is 166721805893. The next prime is 166721805907. The reversal of 166721805900 is 9508127661.

166721805900 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an interprime number because it is at equal distance from previous prime (166721805893) and next prime (166721805907).

It is a Harshad number since it is a multiple of its sum of digits (45).

It is not an unprimeable number, because it can be changed into a prime (166721805907) by changing a digit.

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 119 ways as a sum of consecutive naturals, for example, 4509490 + ... + 4546310.

Almost surely, 2^166721805900 is an apocalyptic number.

166721805900 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 166721805900, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (297785258232).

166721805900 is an abundant number, since it is smaller than the sum of its proper divisors (428848710564).

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

166721805900 is a wasteful number, since it uses less digits than its factorization.

166721805900 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 36903 (or 36887 counting only the distinct ones).

The product of its (nonzero) digits is 181440, while the sum is 45.

The spelling of 166721805900 in words is "one hundred sixty-six billion, seven hundred twenty-one million, eight hundred five thousand, nine hundred".