291191081 has 2 divisors, whose sum is σ = 291191082. Its totient is φ = 291191080.

The previous prime is 291191071. The next prime is 291191101. The reversal of 291191081 is 180191192.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 286151056 + 5040025 = 16916^2 + 2245^2 .

It is a cyclic number.

It is not a de Polignac number, because 291191081 - 2²² = 286996777 is a prime.

It is a super-2 number, since 2×291191081² = 169584491307897122, which contains 22 as substring.

It is a Chen prime.

It is equal to p_15800684 and since 291191081 and 15800684 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (291191071) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 145595540 + 145595541.

It is an arithmetic number, because the mean of its divisors is an integer number (145595541).

Almost surely, 2^291191081 is an apocalyptic number.

It is an amenable number.

291191081 is a deficient number, since it is larger than the sum of its proper divisors (1).

291191081 is an equidigital number, since it uses as much as digits as its factorization.

291191081 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1296, while the sum is 32.

The square root of 291191081 is about 17064.3218734294. The cubic root of 291191081 is about 662.8155513984.

The spelling of 291191081 in words is "two hundred ninety-one million, one hundred ninety-one thousand, eighty-one".