81199744 has 16 divisors (see below), whose sum is σ = 161765370. Its totient is φ = 40599808.

The previous prime is 81199709. The next prime is 81199747. The reversal of 81199744 is 44799118.

It can be written as a sum of positive squares in only one way, i.e., 69089344 + 12110400 = 8312^2 + 3480^2 .

It is a tau number, because it is divible by the number of its divisors (16).

It is a self number, because there is not a number n which added to its sum of digits gives 81199744.

It is not an unprimeable number, because it can be changed into a prime (81199747) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 317059 + ... + 317314.

Almost surely, 2^81199744 is an apocalyptic number.

It is an amenable number.

81199744 is a deficient number, since it is larger than the sum of its proper divisors (80565626).

81199744 is an equidigital number, since it uses as much as digits as its factorization.

81199744 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 634387 (or 634375 counting only the distinct ones).

The product of its digits is 72576, while the sum is 43.

The square root of 81199744 is about 9011.0900561475. The cubic root of 81199744 is about 433.0302343294.

The spelling of 81199744 in words is "eighty-one million, one hundred ninety-nine thousand, seven hundred forty-four".