81928263181 has 2 divisors, whose sum is σ = 81928263182. Its totient is φ = 81928263180.

The previous prime is 81928263139. The next prime is 81928263227. The reversal of 81928263181 is 18136282918.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 63902784100 + 18025479081 = 252790^2 + 134259^2 .

It is a cyclic number.

It is not a de Polignac number, because 81928263181 - 2²³ = 81919874573 is a prime.

It is a super-2 number, since 2×81928263181² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81928263121) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40964131590 + 40964131591.

It is an arithmetic number, because the mean of its divisors is an integer number (40964131591).

Almost surely, 2^81928263181 is an apocalyptic number.

It is an amenable number.

81928263181 is a deficient number, since it is larger than the sum of its proper divisors (1).

81928263181 is an equidigital number, since it uses as much as digits as its factorization.

81928263181 is an evil number, because the sum of its binary digits is even.

The product of its digits is 331776, while the sum is 49.

The spelling of 81928263181 in words is "eighty-one billion, nine hundred twenty-eight million, two hundred sixty-three thousand, one hundred eighty-one".