81228981731 has 2 divisors, whose sum is σ = 81228981732. Its totient is φ = 81228981730.

The previous prime is 81228981709. The next prime is 81228981767. The reversal of 81228981731 is 13718982218.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81228981731 - 2¹⁴ = 81228965347 is a prime.

It is a super-2 number, since 2×81228981731² (a number of 23 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 81228981731.

It is not a weakly prime, because it can be changed into another prime (81228981791) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40614490865 + 40614490866.

It is an arithmetic number, because the mean of its divisors is an integer number (40614490866).

Almost surely, 2^81228981731 is an apocalyptic number.

81228981731 is a deficient number, since it is larger than the sum of its proper divisors (1).

81228981731 is an equidigital number, since it uses as much as digits as its factorization.

81228981731 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 387072, while the sum is 50.

The spelling of 81228981731 in words is "eighty-one billion, two hundred twenty-eight million, nine hundred eighty-one thousand, seven hundred thirty-one".