20173987 has 4 divisors (see below), whose sum is σ = 20188696. Its totient is φ = 20159280.

The previous prime is 20173969. The next prime is 20173997. The reversal of 20173987 is 78937102.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 78937102 = 2 ⋅39468551.

It is a cyclic number.

It is not a de Polignac number, because 20173987 - 2²³ = 11785379 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20173957) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5058 + ... + 8119.

It is an arithmetic number, because the mean of its divisors is an integer number (5047174).

Almost surely, 2^20173987 is an apocalyptic number.

20173987 is a deficient number, since it is larger than the sum of its proper divisors (14709).

20173987 is a wasteful number, since it uses less digits than its factorization.

20173987 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14708.

The product of its (nonzero) digits is 21168, while the sum is 37.

The square root of 20173987 is about 4491.5461703071. The cubic root of 20173987 is about 272.2266124394.

The spelling of 20173987 in words is "twenty million, one hundred seventy-three thousand, nine hundred eighty-seven".