19966515869761 has 2 divisors, whose sum is σ = 19966515869762. Its totient is φ = 19966515869760.

The previous prime is 19966515869693. The next prime is 19966515869771. The reversal of 19966515869761 is 16796851566991.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 13868362200625 + 6098153669136 = 3724025^2 + 2469444^2 .

It is a cyclic number.

It is not a de Polignac number, because 19966515869761 - 2¹³ = 19966515861569 is a prime.

It is not a weakly prime, because it can be changed into another prime (19966515869771) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9983257934880 + 9983257934881.

It is an arithmetic number, because the mean of its divisors is an integer number (9983257934881).

Almost surely, 2^{19966515869761} is an apocalyptic number.

It is an amenable number.

19966515869761 is a deficient number, since it is larger than the sum of its proper divisors (1).

19966515869761 is an equidigital number, since it uses as much as digits as its factorization.

19966515869761 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1322697600, while the sum is 79.

The spelling of 19966515869761 in words is "nineteen trillion, nine hundred sixty-six billion, five hundred fifteen million, eight hundred sixty-nine thousand, seven hundred sixty-one".