1228916891 has 2 divisors, whose sum is σ = 1228916892. Its totient is φ = 1228916890.

The previous prime is 1228916879. The next prime is 1228916917. The reversal of 1228916891 is 1986198221.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 1228916891 - 2¹⁰ = 1228915867 is a prime.

It is not a weakly prime, because it can be changed into another prime (1228916851) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 614458445 + 614458446.

It is an arithmetic number, because the mean of its divisors is an integer number (614458446).

Almost surely, 2^1228916891 is an apocalyptic number.

1228916891 is a deficient number, since it is larger than the sum of its proper divisors (1).

1228916891 is an equidigital number, since it uses as much as digits as its factorization.

1228916891 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 124416, while the sum is 47.

The square root of 1228916891 is about 35055.9109281160. The cubic root of 1228916891 is about 1071.1266820264.

The spelling of 1228916891 in words is "one billion, two hundred twenty-eight million, nine hundred sixteen thousand, eight hundred ninety-one".