81049865 has 12 divisors (see below), whose sum is σ = 105317964. Its totient is φ = 59851584.

The previous prime is 81049853. The next prime is 81049889. The reversal of 81049865 is 56894018.

It can be written as a sum of positive squares in 6 ways, for example, as 13366336 + 67683529 = 3656^2 + 8227^2 .

It is not a de Polignac number, because 81049865 - 2¹⁶ = 80984329 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 47114 + ... + 48803.

It is an arithmetic number, because the mean of its divisors is an integer number (8776497).

Almost surely, 2^81049865 is an apocalyptic number.

It is an amenable number.

81049865 is a deficient number, since it is larger than the sum of its proper divisors (24268099).

81049865 is a wasteful number, since it uses less digits than its factorization.

81049865 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 95948 (or 95935 counting only the distinct ones).

The product of its (nonzero) digits is 69120, while the sum is 41.

The square root of 81049865 is about 9002.7698515512. The cubic root of 81049865 is about 432.7636402551.

The spelling of 81049865 in words is "eighty-one million, forty-nine thousand, eight hundred sixty-five".