166661640 has 96 divisors (see below), whose sum is σ = 543979800. Its totient is φ = 44252160.

The previous prime is 166661609. The next prime is 166661681. The reversal of 166661640 is 46166661.

It can be written as a sum of positive squares in 4 ways, for example, as 113167044 + 53494596 = 10638^2 + 7314^2 .

It is a super-2 number, since 2×166661640² = 55552204494979200, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 166661595 and 166661604.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 95980 + ... + 97700.

Almost surely, 2^166661640 is an apocalyptic number.

166661640 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 166661640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (271989900).

166661640 is an abundant number, since it is smaller than the sum of its proper divisors (377318160).

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

166661640 is a wasteful number, since it uses less digits than its factorization.

166661640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2007 (or 2000 counting only the distinct ones).

The product of its (nonzero) digits is 31104, while the sum is 36.

The square root of 166661640 is about 12909.7498039273. The cubic root of 166661640 is about 550.3156755309.

The spelling of 166661640 in words is "one hundred sixty-six million, six hundred sixty-one thousand, six hundred forty".