291666121 has 2 divisors, whose sum is σ = 291666122. Its totient is φ = 291666120.

The previous prime is 291666113. The next prime is 291666139. The reversal of 291666121 is 121666192.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 291043600 + 622521 = 17060^2 + 789^2 .

It is a cyclic number.

It is not a de Polignac number, because 291666121 - 2³ = 291666113 is a prime.

It is a super-2 number, since 2×291666121² = 170138252278373282, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (291666181) 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, 145833060 + 145833061.

It is an arithmetic number, because the mean of its divisors is an integer number (145833061).

Almost surely, 2^291666121 is an apocalyptic number.

It is an amenable number.

291666121 is a deficient number, since it is larger than the sum of its proper divisors (1).

291666121 is an equidigital number, since it uses as much as digits as its factorization.

291666121 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 7776, while the sum is 34.

The square root of 291666121 is about 17078.2353011077. The cubic root of 291666121 is about 663.1757877465.

The spelling of 291666121 in words is "two hundred ninety-one million, six hundred sixty-six thousand, one hundred twenty-one".