81749523439 has 2 divisors, whose sum is σ = 81749523440. Its totient is φ = 81749523438.

The previous prime is 81749523433. The next prime is 81749523509. The reversal of 81749523439 is 93432594718.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81749523439 - 2⁷ = 81749523311 is a prime.

It is a super-2 number, since 2×81749523439² (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 81749523439.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81749523433) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40874761719 + 40874761720.

It is an arithmetic number, because the mean of its divisors is an integer number (40874761720).

Almost surely, 2^81749523439 is an apocalyptic number.

81749523439 is a deficient number, since it is larger than the sum of its proper divisors (1).

81749523439 is an equidigital number, since it uses as much as digits as its factorization.

81749523439 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 6531840, while the sum is 55.

The spelling of 81749523439 in words is "eighty-one billion, seven hundred forty-nine million, five hundred twenty-three thousand, four hundred thirty-nine".