9971681 has 2 divisors, whose sum is σ = 9971682. Its totient is φ = 9971680.

The previous prime is 9971653. The next prime is 9971683. The reversal of 9971681 is 1861799.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 9891025 + 80656 = 3145^2 + 284^2 .

It is a cyclic number.

It is not a de Polignac number, because 9971681 - 2¹⁸ = 9709537 is a prime.

It is a super-2 number, since 2×9971681² = 198868843931522, which contains 22 as substring.

Together with 9971683, 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 (9971683) 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, 4985840 + 4985841.

It is an arithmetic number, because the mean of its divisors is an integer number (4985841).

Almost surely, 2^9971681 is an apocalyptic number.

It is an amenable number.

9971681 is a deficient number, since it is larger than the sum of its proper divisors (1).

9971681 is an equidigital number, since it uses as much as digits as its factorization.

9971681 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 27216, while the sum is 41.

The square root of 9971681 is about 3157.7968585709. The cubic root of 9971681 is about 215.2399052714.

The spelling of 9971681 in words is "nine million, nine hundred seventy-one thousand, six hundred eighty-one".