166561940 has 12 divisors (see below), whose sum is σ = 349780116. Its totient is φ = 66624768.

The previous prime is 166561939. The next prime is 166561949. The reversal of 166561940 is 49165661.

It can be written as a sum of positive squares in 2 ways, for example, as 27227524 + 139334416 = 5218^2 + 11804^2 .

It is a junction number, because it is equal to n+sod(n) for n = 166561894 and 166561903.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (166561949) 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 3 ways as a sum of consecutive naturals, for example, 4164029 + ... + 4164068.

It is an arithmetic number, because the mean of its divisors is an integer number (29148343).

Almost surely, 2^166561940 is an apocalyptic number.

166561940 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

166561940 is an abundant number, since it is smaller than the sum of its proper divisors (183218176).

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

166561940 is a wasteful number, since it uses less digits than its factorization.

166561940 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8328106 (or 8328104 counting only the distinct ones).

The product of its (nonzero) digits is 38880, while the sum is 38.

The square root of 166561940 is about 12905.8878036344. The cubic root of 166561940 is about 550.2059173862.

The spelling of 166561940 in words is "one hundred sixty-six million, five hundred sixty-one thousand, nine hundred forty".