9217981 has 2 divisors, whose sum is σ = 9217982. Its totient is φ = 9217980.

The previous prime is 9217979. The next prime is 9218017. The reversal of 9217981 is 1897129.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 5736025 + 3481956 = 2395^2 + 1866^2 .

It is a cyclic number.

It is not a de Polignac number, because 9217981 - 2¹ = 9217979 is a prime.

It is a super-2 number, since 2×9217981² = 169942347432722, which contains 22 as substring.

Together with 9217979, it forms a pair of twin primes.

It is a self number, because there is not a number n which added to its sum of digits gives 9217981.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (9217931) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4608990 + 4608991.

It is an arithmetic number, because the mean of its divisors is an integer number (4608991).

Almost surely, 2^9217981 is an apocalyptic number.

It is an amenable number.

9217981 is a deficient number, since it is larger than the sum of its proper divisors (1).

9217981 is an equidigital number, since it uses as much as digits as its factorization.

9217981 is an evil number, because the sum of its binary digits is even.

The product of its digits is 9072, while the sum is 37.

The square root of 9217981 is about 3036.1128108158. The cubic root of 9217981 is about 209.6743327079.

The spelling of 9217981 in words is "nine million, two hundred seventeen thousand, nine hundred eighty-one".