2001855021811 has 2 divisors, whose sum is σ = 2001855021812. Its totient is φ = 2001855021810.

The previous prime is 2001855021797. The next prime is 2001855021923. The reversal of 2001855021811 is 1181205581002.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 2001855021811 - 2¹³ = 2001855013619 is a prime.

It is not a weakly prime, because it can be changed into another prime (2001855021311) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1000927510905 + 1000927510906.

It is an arithmetic number, because the mean of its divisors is an integer number (1000927510906).

Almost surely, 2^{2001855021811} is an apocalyptic number.

2001855021811 is a deficient number, since it is larger than the sum of its proper divisors (1).

2001855021811 is an equidigital number, since it uses as much as digits as its factorization.

2001855021811 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 6400, while the sum is 34.

The spelling of 2001855021811 in words is "two trillion, one billion, eight hundred fifty-five million, twenty-one thousand, eight hundred eleven".