9571981 has 2 divisors, whose sum is σ = 9571982. Its totient is φ = 9571980.

The previous prime is 9571951. The next prime is 9571987. The reversal of 9571981 is 1891759.

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., 9517225 + 54756 = 3085^2 + 234^2 .

It is a cyclic number.

It is not a de Polignac number, because 9571981 - 2⁵ = 9571949 is a prime.

It is a super-2 number, since 2×9571981² = 183245640528722, which contains 22 as substring.

It is an Ulam number.

9571981 is a lucky number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (9571987) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4785990 + 4785991.

It is an arithmetic number, because the mean of its divisors is an integer number (4785991).

Almost surely, 2^9571981 is an apocalyptic number.

It is an amenable number.

9571981 is a deficient number, since it is larger than the sum of its proper divisors (1).

9571981 is an equidigital number, since it uses as much as digits as its factorization.

9571981 is an evil number, because the sum of its binary digits is even.

The product of its digits is 22680, while the sum is 40.

The square root of 9571981 is about 3093.8618262618. The cubic root of 9571981 is about 212.3247440816.

The spelling of 9571981 in words is "nine million, five hundred seventy-one thousand, nine hundred eighty-one".