18816722477561 has 2 divisors, whose sum is σ = 18816722477562. Its totient is φ = 18816722477560.

The previous prime is 18816722477551. The next prime is 18816722477591. The reversal of 18816722477561 is 16577422761881.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13663114213225 + 5153608264336 = 3696365^2 + 2270156^2 .

It is a cyclic number.

It is not a de Polignac number, because 18816722477561 - 2¹⁰ = 18816722476537 is a prime.

It is not a weakly prime, because it can be changed into another prime (18816722477551) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9408361238780 + 9408361238781.

It is an arithmetic number, because the mean of its divisors is an integer number (9408361238781).

Almost surely, 2^{18816722477561} is an apocalyptic number.

It is an amenable number.

18816722477561 is a deficient number, since it is larger than the sum of its proper divisors (1).

18816722477561 is an equidigital number, since it uses as much as digits as its factorization.

18816722477561 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 63221760, while the sum is 65.

The spelling of 18816722477561 in words is "eighteen trillion, eight hundred sixteen billion, seven hundred twenty-two million, four hundred seventy-seven thousand, five hundred sixty-one".