81544665311 has 2 divisors, whose sum is σ = 81544665312. Its totient is φ = 81544665310.

The previous prime is 81544665283. The next prime is 81544665347. The reversal of 81544665311 is 11356644518.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81544665311 - 2⁶ = 81544665247 is a prime.

It is a Sophie Germain prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81544668311) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40772332655 + 40772332656.

It is an arithmetic number, because the mean of its divisors is an integer number (40772332656).

Almost surely, 2^81544665311 is an apocalyptic number.

81544665311 is a deficient number, since it is larger than the sum of its proper divisors (1).

81544665311 is an equidigital number, since it uses as much as digits as its factorization.

81544665311 is an evil number, because the sum of its binary digits is even.

The product of its digits is 345600, while the sum is 44.

The spelling of 81544665311 in words is "eighty-one billion, five hundred forty-four million, six hundred sixty-five thousand, three hundred eleven".