20711987 has 2 divisors, whose sum is σ = 20711988. Its totient is φ = 20711986.

The previous prime is 20711981. The next prime is 20712019. The reversal of 20711987 is 78911702.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20711987 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (20711981) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10355993 + 10355994.

It is an arithmetic number, because the mean of its divisors is an integer number (10355994).

Almost surely, 2^20711987 is an apocalyptic number.

20711987 is a deficient number, since it is larger than the sum of its proper divisors (1).

20711987 is an equidigital number, since it uses as much as digits as its factorization.

20711987 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 7056, while the sum is 35.

The square root of 20711987 is about 4551.0424080643. The cubic root of 20711987 is about 274.6253277783.

The spelling of 20711987 in words is "twenty million, seven hundred eleven thousand, nine hundred eighty-seven".