81124865 has 4 divisors (see below), whose sum is σ = 97349844. Its totient is φ = 64899888.

The previous prime is 81124859. The next prime is 81124891. The reversal of 81124865 is 56842118.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 21464689 + 59660176 = 4633^2 + 7724^2 .

It is a cyclic number.

It is not a de Polignac number, because 81124865 - 2¹⁴ = 81108481 is a prime.

It is a Duffinian 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, 8112482 + ... + 8112491.

It is an arithmetic number, because the mean of its divisors is an integer number (24337461).

Almost surely, 2^81124865 is an apocalyptic number.

It is an amenable number.

81124865 is a deficient number, since it is larger than the sum of its proper divisors (16224979).

81124865 is a wasteful number, since it uses less digits than its factorization.

81124865 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16224978.

The product of its digits is 15360, while the sum is 35.

The square root of 81124865 is about 9006.9342731031. The cubic root of 81124865 is about 432.8970859499.

The spelling of 81124865 in words is "eighty-one million, one hundred twenty-four thousand, eight hundred sixty-five".