81015749 has 2 divisors, whose sum is σ = 81015750. Its totient is φ = 81015748.

The previous prime is 81015709. The next prime is 81015787. The reversal of 81015749 is 94751018.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 80550625 + 465124 = 8975^2 + 682^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81015749 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81015709) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40507874 + 40507875.

It is an arithmetic number, because the mean of its divisors is an integer number (40507875).

Almost surely, 2^81015749 is an apocalyptic number.

It is an amenable number.

81015749 is a deficient number, since it is larger than the sum of its proper divisors (1).

81015749 is an equidigital number, since it uses as much as digits as its factorization.

81015749 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 10080, while the sum is 35.

The square root of 81015749 is about 9000.8749019193. The cubic root of 81015749 is about 432.7029112361.

The spelling of 81015749 in words is "eighty-one million, fifteen thousand, seven hundred forty-nine".