20011987 has 2 divisors, whose sum is σ = 20011988. Its totient is φ = 20011986.

The previous prime is 20011967. The next prime is 20011993. The reversal of 20011987 is 78911002.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 20011987 - 2¹¹ = 20009939 is a prime.

It is not a weakly prime, because it can be changed into another prime (20011967) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10005993 + 10005994.

It is an arithmetic number, because the mean of its divisors is an integer number (10005994).

Almost surely, 2^20011987 is an apocalyptic number.

20011987 is a deficient number, since it is larger than the sum of its proper divisors (1).

20011987 is an equidigital number, since it uses as much as digits as its factorization.

20011987 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1008, while the sum is 28.

The square root of 20011987 is about 4473.4759415917. The cubic root of 20011987 is about 271.4959803689.

Adding to 20011987 its reverse (78911002), we get a palindrome (98922989).

The spelling of 20011987 in words is "twenty million, eleven thousand, nine hundred eighty-seven".