20564987 has 2 divisors, whose sum is σ = 20564988. Its totient is φ = 20564986.

The previous prime is 20564969. The next prime is 20564989. The reversal of 20564987 is 78946502.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 20564987 - 2⁶ = 20564923 is a prime.

Together with 20564989, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (20564989) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10282493 + 10282494.

It is an arithmetic number, because the mean of its divisors is an integer number (10282494).

Almost surely, 2^20564987 is an apocalyptic number.

20564987 is a deficient number, since it is larger than the sum of its proper divisors (1).

20564987 is an equidigital number, since it uses as much as digits as its factorization.

20564987 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 120960, while the sum is 41.

The square root of 20564987 is about 4534.8635040098. The cubic root of 20564987 is about 273.9740815877.

The spelling of 20564987 in words is "twenty million, five hundred sixty-four thousand, nine hundred eighty-seven".