1916218891 has 2 divisors, whose sum is σ = 1916218892. Its totient is φ = 1916218890.

The previous prime is 1916218859. The next prime is 1916218939. The reversal of 1916218891 is 1988126191.

It is a weak prime.

It is an emirp because it is prime and its reverse (1988126191) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1916218891 - 2⁵ = 1916218859 is a prime.

It is not a weakly prime, because it can be changed into another prime (1916218691) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 958109445 + 958109446.

It is an arithmetic number, because the mean of its divisors is an integer number (958109446).

Almost surely, 2^1916218891 is an apocalyptic number.

1916218891 is a deficient number, since it is larger than the sum of its proper divisors (1).

1916218891 is an equidigital number, since it uses as much as digits as its factorization.

1916218891 is an evil number, because the sum of its binary digits is even.

The product of its digits is 62208, while the sum is 46.

The square root of 1916218891 is about 43774.6375313377. The cubic root of 1916218891 is about 1242.0765783785.

The spelling of 1916218891 in words is "one billion, nine hundred sixteen million, two hundred eighteen thousand, eight hundred ninety-one".