81000961 has 2 divisors, whose sum is σ = 81000962. Its totient is φ = 81000960.

The previous prime is 81000929. The next prime is 81000979. The reversal of 81000961 is 16900018.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 81000000 + 961 = 9000^2 + 31^2 .

It is a cyclic number.

It is not a de Polignac number, because 81000961 - 2⁵ = 81000929 is a prime.

It is a super-2 number, since 2×81000961² = 13122311365847042, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (81000911) 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, 40500480 + 40500481.

It is an arithmetic number, because the mean of its divisors is an integer number (40500481).

Almost surely, 2^81000961 is an apocalyptic number.

It is an amenable number.

81000961 is a deficient number, since it is larger than the sum of its proper divisors (1).

81000961 is an equidigital number, since it uses as much as digits as its factorization.

81000961 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 432, while the sum is 25.

The square root of 81000961 is about 9000.0533887305. The cubic root of 81000961 is about 432.6765821988.

Adding to 81000961 its reverse (16900018), we get a palindrome (97900979).

The spelling of 81000961 in words is "eighty-one million, nine hundred sixty-one", and thus it is an aban number.