81863912773 has 2 divisors, whose sum is σ = 81863912774. Its totient is φ = 81863912772.

The previous prime is 81863912761. The next prime is 81863912783. The reversal of 81863912773 is 37721936818.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 80955613729 + 908299044 = 284527^2 + 30138^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81863912773 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81863912723) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40931956386 + 40931956387.

It is an arithmetic number, because the mean of its divisors is an integer number (40931956387).

Almost surely, 2^81863912773 is an apocalyptic number.

It is an amenable number.

81863912773 is a deficient number, since it is larger than the sum of its proper divisors (1).

81863912773 is an equidigital number, since it uses as much as digits as its factorization.

81863912773 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3048192, while the sum is 55.

The spelling of 81863912773 in words is "eighty-one billion, eight hundred sixty-three million, nine hundred twelve thousand, seven hundred seventy-three".