81765625 has 14 divisors (see below), whose sum is σ = 102225254. Its totient is φ = 65400000.

The previous prime is 81765613. The next prime is 81765637. The reversal of 81765625 is 52656718.

It is an interprime number because it is at equal distance from previous prime (81765613) and next prime (81765637).

It can be written as a sum of positive squares in 7 ways, for example, as 76247824 + 5517801 = 8732^2 + 2349^2 .

It is not a de Polignac number, because 81765625 - 2¹⁹ = 81241337 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 (17) of ones.

It is a polite number, since it can be written in 13 ways as a sum of consecutive naturals, for example, 13009 + ... + 18241.

Almost surely, 2^81765625 is an apocalyptic number.

It is an amenable number.

81765625 is a deficient number, since it is larger than the sum of its proper divisors (20459629).

81765625 is an frugal number, since it uses more digits than its factorization.

81765625 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5263 (or 5238 counting only the distinct ones).

The product of its digits is 100800, while the sum is 40.

The square root of 81765625 is about 9042.4346832034. The cubic root of 81765625 is about 434.0338357673.

It can be divided in two parts, 81 and 765625, that multiplied together give a square (62015625 = 7875²).

The spelling of 81765625 in words is "eighty-one million, seven hundred sixty-five thousand, six hundred twenty-five".