20009987 has 2 divisors, whose sum is σ = 20009988. Its totient is φ = 20009986.

The previous prime is 20009981. The next prime is 20009999. The reversal of 20009987 is 78990002.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20009987 - 2⁶ = 20009923 is a prime.

It is not a weakly prime, because it can be changed into another prime (20009981) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10004993 + 10004994.

It is an arithmetic number, because the mean of its divisors is an integer number (10004994).

Almost surely, 2^20009987 is an apocalyptic number.

20009987 is a deficient number, since it is larger than the sum of its proper divisors (1).

20009987 is an equidigital number, since it uses as much as digits as its factorization.

20009987 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 9072, while the sum is 35.

The square root of 20009987 is about 4473.2523961878. The cubic root of 20009987 is about 271.4869356223.

Adding to 20009987 its reverse (78990002), we get a palindrome (98999989).

The spelling of 20009987 in words is "twenty million, nine thousand, nine hundred eighty-seven".