20172158 has 4 divisors (see below), whose sum is σ = 30258240. Its totient is φ = 10086078.

The previous prime is 20172157. The next prime is 20172161. The reversal of 20172158 is 85127102.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 85127102 = 2 ⋅42563551.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20172157) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5043038 + ... + 5043041.

It is an arithmetic number, because the mean of its divisors is an integer number (7564560).

Almost surely, 2^20172158 is an apocalyptic number.

20172158 is a deficient number, since it is larger than the sum of its proper divisors (10086082).

20172158 is a wasteful number, since it uses less digits than its factorization.

20172158 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10086081.

The product of its (nonzero) digits is 1120, while the sum is 26.

The square root of 20172158 is about 4491.3425609722. The cubic root of 20172158 is about 272.2183853841.

The spelling of 20172158 in words is "twenty million, one hundred seventy-two thousand, one hundred fifty-eight".