291689891 has 2 divisors, whose sum is σ = 291689892. Its totient is φ = 291689890.

The previous prime is 291689869. The next prime is 291689897. The reversal of 291689891 is 198986192.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-291689891 is a prime.

It is not a weakly prime, because it can be changed into another prime (291689897) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 145844945 + 145844946.

It is an arithmetic number, because the mean of its divisors is an integer number (145844946).

Almost surely, 2^291689891 is an apocalyptic number.

291689891 is a deficient number, since it is larger than the sum of its proper divisors (1).

291689891 is an equidigital number, since it uses as much as digits as its factorization.

291689891 is an evil number, because the sum of its binary digits is even.

The product of its digits is 559872, while the sum is 53.

The square root of 291689891 is about 17078.9312019224. The cubic root of 291689891 is about 663.1938029348.

The spelling of 291689891 in words is "two hundred ninety-one million, six hundred eighty-nine thousand, eight hundred ninety-one".