81550076878357 has 2 divisors, whose sum is σ = 81550076878358. Its totient is φ = 81550076878356.

The previous prime is 81550076878331. The next prime is 81550076878423. The reversal of 81550076878357 is 75387867005518.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 59476702348996 + 22073374529361 = 7712114^2 + 4698231^2 .

It is a cyclic number.

It is not a de Polignac number, because 81550076878357 - 2³⁹ = 81000321064469 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81550076878307) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40775038439178 + 40775038439179.

It is an arithmetic number, because the mean of its divisors is an integer number (40775038439179).

Almost surely, 2^{81550076878357} is an apocalyptic number.

It is an amenable number.

81550076878357 is a deficient number, since it is larger than the sum of its proper divisors (1).

81550076878357 is an equidigital number, since it uses as much as digits as its factorization.

81550076878357 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 395136000, while the sum is 70.

The spelling of 81550076878357 in words is "eighty-one trillion, five hundred fifty billion, seventy-six million, eight hundred seventy-eight thousand, three hundred fifty-seven".