166809553 has 4 divisors (see below), whose sum is σ = 167656500. Its totient is φ = 165962608.

The previous prime is 166809509. The next prime is 166809557. The reversal of 166809553 is 355908661.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 109474369 + 57335184 = 10463^2 + 7572^2 .

It is a cyclic number.

It is not a de Polignac number, because 166809553 - 2²⁵ = 133255121 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (166809557) 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, 423178 + ... + 423571.

It is an arithmetic number, because the mean of its divisors is an integer number (41914125).

Almost surely, 2^166809553 is an apocalyptic number.

It is an amenable number.

166809553 is a deficient number, since it is larger than the sum of its proper divisors (846947).

166809553 is an equidigital number, since it uses as much as digits as its factorization.

166809553 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 846946.

The product of its (nonzero) digits is 194400, while the sum is 43.

The square root of 166809553 is about 12915.4772656685. The cubic root of 166809553 is about 550.4784299871.

The spelling of 166809553 in words is "one hundred sixty-six million, eight hundred nine thousand, five hundred fifty-three".