19811664427 has 2 divisors, whose sum is σ = 19811664428. Its totient is φ = 19811664426.

The previous prime is 19811664421. The next prime is 19811664451. The reversal of 19811664427 is 72446611891.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 19811664427 - 2¹¹ = 19811662379 is a prime.

It is not a weakly prime, because it can be changed into another prime (19811664421) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9905832213 + 9905832214.

It is an arithmetic number, because the mean of its divisors is an integer number (9905832214).

Almost surely, 2^19811664427 is an apocalyptic number.

19811664427 is a deficient number, since it is larger than the sum of its proper divisors (1).

19811664427 is an equidigital number, since it uses as much as digits as its factorization.

19811664427 is an evil number, because the sum of its binary digits is even.

The product of its digits is 580608, while the sum is 49.

The spelling of 19811664427 in words is "nineteen billion, eight hundred eleven million, six hundred sixty-four thousand, four hundred twenty-seven".