166661641 has 4 divisors (see below), whose sum is σ = 166961412. Its totient is φ = 166361872.

The previous prime is 166661609. The next prime is 166661681. The reversal of 166661641 is 146166661.

166661641 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 146166661 = 6607 ⋅22123.

It can be written as a sum of positive squares in 2 ways, for example, as 107433225 + 59228416 = 10365^2 + 7696^2 .

It is a cyclic number.

It is not a de Polignac number, because 166661641 - 2⁵ = 166661609 is a prime.

It is a super-2 number, since 2×166661641² = 55552205161625762, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 166661641.

It is not an unprimeable number, because it can be changed into a prime (166661681) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 149050 + ... + 150163.

It is an arithmetic number, because the mean of its divisors is an integer number (41740353).

Almost surely, 2^166661641 is an apocalyptic number.

It is an amenable number.

166661641 is a deficient number, since it is larger than the sum of its proper divisors (299771).

166661641 is an equidigital number, since it uses as much as digits as its factorization.

166661641 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 299770.

The product of its digits is 31104, while the sum is 37.

The square root of 166661641 is about 12909.7498426577. The cubic root of 166661641 is about 550.3156766316.

The spelling of 166661641 in words is "one hundred sixty-six million, six hundred sixty-one thousand, six hundred forty-one".