20556166 has 4 divisors (see below), whose sum is σ = 30834252. Its totient is φ = 10278082.

The previous prime is 20556161. The next prime is 20556191. The reversal of 20556166 is 66165502.

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

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20556161) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5139040 + ... + 5139043.

It is an arithmetic number, because the mean of its divisors is an integer number (7708563).

Almost surely, 2^20556166 is an apocalyptic number.

20556166 is a deficient number, since it is larger than the sum of its proper divisors (10278086).

20556166 is a wasteful number, since it uses less digits than its factorization.

20556166 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10278085.

The product of its (nonzero) digits is 10800, while the sum is 31.

The square root of 20556166 is about 4533.8908235642. The cubic root of 20556166 is about 273.9349038176.

The spelling of 20556166 in words is "twenty million, five hundred fifty-six thousand, one hundred sixty-six".