20166861 has 32 divisors (see below), whose sum is σ = 32699520. Its totient is φ = 10886400.

The previous prime is 20166851. The next prime is 20166877. The reversal of 20166861 is 16866102.

It is not a de Polignac number, because 20166861 - 2⁵ = 20166829 is a prime.

It is a Smith number, since the sum of its digits (30) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20166821) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 11631 + ... + 13251.

It is an arithmetic number, because the mean of its divisors is an integer number (1021860).

Almost surely, 2^20166861 is an apocalyptic number.

It is an amenable number.

20166861 is a deficient number, since it is larger than the sum of its proper divisors (12532659).

20166861 is a wasteful number, since it uses less digits than its factorization.

20166861 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1677.

The product of its (nonzero) digits is 3456, while the sum is 30.

The square root of 20166861 is about 4490.7528322098. The cubic root of 20166861 is about 272.1945560543.

The spelling of 20166861 in words is "twenty million, one hundred sixty-six thousand, eight hundred sixty-one".