81169825 has 18 divisors (see below), whose sum is σ = 110636582. Its totient is φ = 59030400.

The previous prime is 81169819. The next prime is 81169831. The reversal of 81169825 is 52896118.

It is an interprime number because it is at equal distance from previous prime (81169819) and next prime (81169831).

It can be written as a sum of positive squares in 3 ways, for example, as 7744 + 81162081 = 88^2 + 9009^2 .

It is not a de Polignac number, because 81169825 - 2⁹ = 81169313 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 17 ways as a sum of consecutive naturals, for example, 10392 + ... + 16441.

Almost surely, 2^81169825 is an apocalyptic number.

It is an amenable number.

81169825 is a deficient number, since it is larger than the sum of its proper divisors (29466757).

81169825 is a wasteful number, since it uses less digits than its factorization.

81169825 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26865 (or 26849 counting only the distinct ones).

The product of its digits is 34560, while the sum is 40.

The square root of 81169825 is about 9009.4297821782. The cubic root of 81169825 is about 432.9770427694.

The spelling of 81169825 in words is "eighty-one million, one hundred sixty-nine thousand, eight hundred twenty-five".