166257778 has 4 divisors (see below), whose sum is σ = 249386670. Its totient is φ = 83128888.

The previous prime is 166257703. The next prime is 166257779. The reversal of 166257778 is 877752661.

It is a happy number.

166257778 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: 877752661 = 829 ⋅1058809.

It can be written as a sum of positive squares in only one way, i.e., 144793089 + 21464689 = 12033^2 + 4633^2 .

It is a Smith number, since the sum of its digits (49) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is not an unprimeable number, because it can be changed into a prime (166257779) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 41564443 + ... + 41564446.

Almost surely, 2^166257778 is an apocalyptic number.

166257778 is a deficient number, since it is larger than the sum of its proper divisors (83128892).

166257778 is an equidigital number, since it uses as much as digits as its factorization.

166257778 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 83128891.

The product of its digits is 987840, while the sum is 49.

The square root of 166257778 is about 12894.0985726029. The cubic root of 166257778 is about 549.8707994039.

The spelling of 166257778 in words is "one hundred sixty-six million, two hundred fifty-seven thousand, seven hundred seventy-eight".