6563981 has 2 divisors, whose sum is σ = 6563982. Its totient is φ = 6563980.

The previous prime is 6563957. The next prime is 6563983. The reversal of 6563981 is 1893656.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 6375625 + 188356 = 2525^2 + 434^2 .

It is a cyclic number.

It is not a de Polignac number, because 6563981 - 2¹⁸ = 6301837 is a prime.

It is a super-2 number, since 2×6563981² = 86171693136722, which contains 22 as substring.

Together with 6563983, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (6563983) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3281990 + 3281991.

It is an arithmetic number, because the mean of its divisors is an integer number (3281991).

Almost surely, 2^6563981 is an apocalyptic number.

It is an amenable number.

6563981 is a deficient number, since it is larger than the sum of its proper divisors (1).

6563981 is an equidigital number, since it uses as much as digits as its factorization.

6563981 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 38880, while the sum is 38.

The square root of 6563981 is about 2562.0267367848. The cubic root of 6563981 is about 187.2358924561.

It can be divided in two parts, 65 and 63981, that added together give a palindrome (64046).

The spelling of 6563981 in words is "six million, five hundred sixty-three thousand, nine hundred eighty-one".