81077612525381 has 2 divisors, whose sum is σ = 81077612525382. Its totient is φ = 81077612525380.

The previous prime is 81077612525363. The next prime is 81077612525383. The reversal of 81077612525381 is 18352521677018.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 79826469608356 + 1251142917025 = 8934566^2 + 1118545^2 .

It is a cyclic number.

It is not a de Polignac number, because 81077612525381 - 2¹⁰ = 81077612524357 is a prime.

It is a super-2 number, since 2×81077612525381² (a number of 29 digits) contains 22 as substring.

Together with 81077612525383, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81077612525383) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40538806262690 + 40538806262691.

It is an arithmetic number, because the mean of its divisors is an integer number (40538806262691).

Almost surely, 2^{81077612525381} is an apocalyptic number.

It is an amenable number.

81077612525381 is a deficient number, since it is larger than the sum of its proper divisors (1).

81077612525381 is an equidigital number, since it uses as much as digits as its factorization.

81077612525381 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 5644800, while the sum is 56.

The spelling of 81077612525381 in words is "eighty-one trillion, seventy-seven billion, six hundred twelve million, five hundred twenty-five thousand, three hundred eighty-one".