20005987 has 4 divisors (see below), whose sum is σ = 20334016. Its totient is φ = 19677960.

The previous prime is 20005981. The next prime is 20006003. The reversal of 20005987 is 78950002.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 78950002 = 2 ⋅39475001.

It is a cyclic number.

It is not a de Polignac number, because 20005987 - 2¹⁹ = 19481699 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20005981) 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, 163923 + ... + 164044.

It is an arithmetic number, because the mean of its divisors is an integer number (5083504).

Almost surely, 2^20005987 is an apocalyptic number.

20005987 is a deficient number, since it is larger than the sum of its proper divisors (328029).

20005987 is an equidigital number, since it uses as much as digits as its factorization.

20005987 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 328028.

The product of its (nonzero) digits is 5040, while the sum is 31.

The square root of 20005987 is about 4472.8052718624. The cubic root of 20005987 is about 271.4688443211.

Adding to 20005987 its reverse (78950002), we get a palindrome (98955989).

The spelling of 20005987 in words is "twenty million, five thousand, nine hundred eighty-seven".