981009581 has 2 divisors, whose sum is σ = 981009582. Its totient is φ = 981009580.

The previous prime is 981009559. The next prime is 981009587. The reversal of 981009581 is 185900189.

981009581 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 514881481 + 466128100 = 22691^2 + 21590^2 .

It is an emirp because it is prime and its reverse (185900189) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 981009581 - 2⁶ = 981009517 is a prime.

It is a super-2 number, since 2×981009581² = 1924759596027591122, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (981009587) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 490504790 + 490504791.

It is an arithmetic number, because the mean of its divisors is an integer number (490504791).

Almost surely, 2^981009581 is an apocalyptic number.

It is an amenable number.

981009581 is a deficient number, since it is larger than the sum of its proper divisors (1).

981009581 is an equidigital number, since it uses as much as digits as its factorization.

981009581 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 25920, while the sum is 41.

The square root of 981009581 is about 31321.0724752522. The cubic root of 981009581 is about 993.6293614824.

The spelling of 981009581 in words is "nine hundred eighty-one million, nine thousand, five hundred eighty-one".