166561836 has 24 divisors (see below), whose sum is σ = 444165120. Its totient is φ = 47589072.

The previous prime is 166561831. The next prime is 166561859. The reversal of 166561836 is 638165661.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is not an unprimeable number, because it can be changed into a prime (166561831) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 991356 + ... + 991523.

It is an arithmetic number, because the mean of its divisors is an integer number (18506880).

Almost surely, 2^166561836 is an apocalyptic number.

It is an amenable number.

166561836 is an abundant number, since it is smaller than the sum of its proper divisors (277603284).

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

166561836 is a wasteful number, since it uses less digits than its factorization.

166561836 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1982893 (or 1982891 counting only the distinct ones).

The product of its digits is 155520, while the sum is 42.

The square root of 166561836 is about 12905.8837744650. The cubic root of 166561836 is about 550.2058028714.

The spelling of 166561836 in words is "one hundred sixty-six million, five hundred sixty-one thousand, eight hundred thirty-six".