81049765 has 4 divisors (see below), whose sum is σ = 97259724. Its totient is φ = 64839808.

The previous prime is 81049757. The next prime is 81049799. The reversal of 81049765 is 56794018.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 56794018 = 2 ⋅28397009.

It can be written as a sum of positive squares in 2 ways, for example, as 55100929 + 25948836 = 7423^2 + 5094^2 .

It is a cyclic number.

It is not a de Polignac number, because 81049765 - 2³ = 81049757 is a prime.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

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 in 3 ways as a sum of consecutive naturals, for example, 8104972 + ... + 8104981.

It is an arithmetic number, because the mean of its divisors is an integer number (24314931).

Almost surely, 2^81049765 is an apocalyptic number.

It is an amenable number.

81049765 is a deficient number, since it is larger than the sum of its proper divisors (16209959).

81049765 is a wasteful number, since it uses less digits than its factorization.

81049765 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16209958.

The product of its (nonzero) digits is 60480, while the sum is 40.

The square root of 81049765 is about 9002.7642977032. The cubic root of 81049765 is about 432.7634622726.

The spelling of 81049765 in words is "eighty-one million, forty-nine thousand, seven hundred sixty-five".