81005025 has 24 divisors (see below), whose sum is σ = 137552704. Its totient is φ = 42033600.

The previous prime is 81005009. The next prime is 81005039. The reversal of 81005025 is 52050018.

It is not a de Polignac number, because 81005025 - 2⁴ = 81005009 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 81004992 and 81005010.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 11821 + ... + 17370.

Almost surely, 2^81005025 is an apocalyptic number.

It is an amenable number.

81005025 is a deficient number, since it is larger than the sum of its proper divisors (56547679).

81005025 is a wasteful number, since it uses less digits than its factorization.

81005025 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 29241 (or 29236 counting only the distinct ones).

The product of its (nonzero) digits is 400, while the sum is 21.

The square root of 81005025 is about 9000.2791623371. The cubic root of 81005025 is about 432.6838181962.

The spelling of 81005025 in words is "eighty-one million, five thousand, twenty-five".