20717158187 has 4 divisors (see below), whose sum is σ = 22600536216. Its totient is φ = 18833780160.

The previous prime is 20717158183. The next prime is 20717158199. The reversal of 20717158187 is 78185171702.

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

It is a cyclic number.

It is not a de Polignac number, because 20717158187 - 2² = 20717158183 is a prime.

It is a super-2 number, since 2×20717158187² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20717158183) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 941688998 + ... + 941689019.

It is an arithmetic number, because the mean of its divisors is an integer number (5650134054).

Almost surely, 2^20717158187 is an apocalyptic number.

20717158187 is a deficient number, since it is larger than the sum of its proper divisors (1883378029).

20717158187 is a wasteful number, since it uses less digits than its factorization.

20717158187 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1883378028.

The product of its (nonzero) digits is 219520, while the sum is 47.

The spelling of 20717158187 in words is "twenty billion, seven hundred seventeen million, one hundred fifty-eight thousand, one hundred eighty-seven".