81381255013 has 2 divisors, whose sum is σ = 81381255014. Its totient is φ = 81381255012.

The previous prime is 81381255001. The next prime is 81381255077. The reversal of 81381255013 is 31055218318.

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., 43683926049 + 37697328964 = 209007^2 + 194158^2 .

It is a cyclic number.

It is not a de Polignac number, because 81381255013 - 2²¹ = 81379157861 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81381255083) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40690627506 + 40690627507.

It is an arithmetic number, because the mean of its divisors is an integer number (40690627507).

Almost surely, 2^81381255013 is an apocalyptic number.

It is an amenable number.

81381255013 is a deficient number, since it is larger than the sum of its proper divisors (1).

81381255013 is an equidigital number, since it uses as much as digits as its factorization.

81381255013 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 28800, while the sum is 37.

The spelling of 81381255013 in words is "eighty-one billion, three hundred eighty-one million, two hundred fifty-five thousand, thirteen".