81331025 has 6 divisors (see below), whose sum is σ = 100850502. Its totient is φ = 65064800.

The previous prime is 81330989. The next prime is 81331027. The reversal of 81331025 is 52013318.

It can be written as a sum of positive squares in 3 ways, for example, as 456976 + 80874049 = 676^2 + 8993^2 .

It is not a de Polignac number, because 81331025 - 2⁶ = 81330961 is a prime.

It is a super-2 number, since 2×81331025² = 13229471255101250, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81331027) by changing a digit.

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 5 ways as a sum of consecutive naturals, for example, 1626596 + ... + 1626645.

It is an arithmetic number, because the mean of its divisors is an integer number (16808417).

Almost surely, 2^81331025 is an apocalyptic number.

It is an amenable number.

81331025 is a deficient number, since it is larger than the sum of its proper divisors (19519477).

81331025 is a wasteful number, since it uses less digits than its factorization.

81331025 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3253251 (or 3253246 counting only the distinct ones).

The product of its (nonzero) digits is 720, while the sum is 23.

The square root of 81331025 is about 9018.3715270552. The cubic root of 81331025 is about 433.2634782203.

The spelling of 81331025 in words is "eighty-one million, three hundred thirty-one thousand, twenty-five".