291907981 has 2 divisors, whose sum is σ = 291907982. Its totient is φ = 291907980.

The previous prime is 291907961. The next prime is 291907999. The reversal of 291907981 is 189709192.

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., 244766025 + 47141956 = 15645^2 + 6866^2 .

It is a cyclic number.

It is not a de Polignac number, because 291907981 - 2⁵ = 291907949 is a prime.

It is a super-2 number, since 2×291907981² = 170420538742992722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (291907961) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 145953990 + 145953991.

It is an arithmetic number, because the mean of its divisors is an integer number (145953991).

Almost surely, 2^291907981 is an apocalyptic number.

It is an amenable number.

291907981 is a deficient number, since it is larger than the sum of its proper divisors (1).

291907981 is an equidigital number, since it uses as much as digits as its factorization.

291907981 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 81648, while the sum is 46.

The square root of 291907981 is about 17085.3147761462. The cubic root of 291907981 is about 663.3590468107.

The spelling of 291907981 in words is "two hundred ninety-one million, nine hundred seven thousand, nine hundred eighty-one".