1817922031561 has 2 divisors, whose sum is σ = 1817922031562. Its totient is φ = 1817922031560.

The previous prime is 1817922031559. The next prime is 1817922031637. The reversal of 1817922031561 is 1651302297181.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1782118201600 + 35803829961 = 1334960^2 + 189219^2 .

It is a cyclic number.

It is not a de Polignac number, because 1817922031561 - 2¹ = 1817922031559 is a prime.

Together with 1817922031559, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (1817922031511) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 908961015780 + 908961015781.

It is an arithmetic number, because the mean of its divisors is an integer number (908961015781).

Almost surely, 2^{1817922031561} is an apocalyptic number.

It is an amenable number.

1817922031561 is a deficient number, since it is larger than the sum of its proper divisors (1).

1817922031561 is an equidigital number, since it uses as much as digits as its factorization.

1817922031561 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 181440, while the sum is 46.

The spelling of 1817922031561 in words is "one trillion, eight hundred seventeen billion, nine hundred twenty-two million, thirty-one thousand, five hundred sixty-one".