19645946891 has 2 divisors, whose sum is σ = 19645946892. Its totient is φ = 19645946890.

The previous prime is 19645946839. The next prime is 19645946911. The reversal of 19645946891 is 19864954691.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 19645946891 - 2³⁴ = 2466077707 is a prime.

It is not a weakly prime, because it can be changed into another prime (19645946821) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9822973445 + 9822973446.

It is an arithmetic number, because the mean of its divisors is an integer number (9822973446).

Almost surely, 2^19645946891 is an apocalyptic number.

19645946891 is a deficient number, since it is larger than the sum of its proper divisors (1).

19645946891 is an equidigital number, since it uses as much as digits as its factorization.

19645946891 is an evil number, because the sum of its binary digits is even.

The product of its digits is 16796160, while the sum is 62.

The spelling of 19645946891 in words is "nineteen billion, six hundred forty-five million, nine hundred forty-six thousand, eight hundred ninety-one".