81025381 has 2 divisors, whose sum is σ = 81025382. Its totient is φ = 81025380.

The previous prime is 81025379. The next prime is 81025403. The reversal of 81025381 is 18352018.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 74476900 + 6548481 = 8630^2 + 2559^2 .

It is a cyclic number.

It is not a de Polignac number, because 81025381 - 2¹ = 81025379 is a prime.

It is a super-2 number, since 2×81025381² = 13130224732390322, which contains 22 as substring.

Together with 81025379, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81025781) by changing a digit.

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 as a sum of consecutive naturals, namely, 40512690 + 40512691.

It is an arithmetic number, because the mean of its divisors is an integer number (40512691).

Almost surely, 2^81025381 is an apocalyptic number.

It is an amenable number.

81025381 is a deficient number, since it is larger than the sum of its proper divisors (1).

81025381 is an equidigital number, since it uses as much as digits as its factorization.

81025381 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1920, while the sum is 28.

The square root of 81025381 is about 9001.4099451142. The cubic root of 81025381 is about 432.7200586399.

Adding to 81025381 its reverse (18352018), we get a palindrome (99377399).

It can be divided in two parts, 81025 and 381, that added together give a triangular number (81406 = T₄₀₃).

The spelling of 81025381 in words is "eighty-one million, twenty-five thousand, three hundred eighty-one".