166561236 has 36 divisors (see below), whose sum is σ = 421421364. Its totient is φ = 55468800.

The previous prime is 166561217. The next prime is 166561237. The reversal of 166561236 is 632165661.

166561236 is a `hidden beast` number, since 1 + 6 + 6 + 5 + 612 + 36 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 136749636 + 29811600 = 11694^2 + 5460^2 .

It is a tau number, because it is divible by the number of its divisors (36).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a self number, because there is not a number n which added to its sum of digits gives 166561236.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (166561237) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 75996 + ... + 78156.

It is an arithmetic number, because the mean of its divisors is an integer number (11706149).

Almost surely, 2^166561236 is an apocalyptic number.

It is an amenable number.

166561236 is an abundant number, since it is smaller than the sum of its proper divisors (254860128).

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

166561236 is a wasteful number, since it uses less digits than its factorization.

166561236 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4312 (or 4307 counting only the distinct ones).

The product of its digits is 38880, while the sum is 36.

The square root of 166561236 is about 12905.8605292324. The cubic root of 166561236 is about 550.2051422081.

The spelling of 166561236 in words is "one hundred sixty-six million, five hundred sixty-one thousand, two hundred thirty-six".