81243181 has 8 divisors (see below), whose sum is σ = 86095800. Its totient is φ = 76527360.

The previous prime is 81243179. The next prime is 81243191. The reversal of 81243181 is 18134218.

It can be written as a sum of positive squares in 4 ways, for example, as 13032100 + 68211081 = 3610^2 + 8259^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 81243181 - 2¹ = 81243179 is a prime.

It is a super-2 number, since 2×81243181² = 13200908917997522, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81243121) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 32976 + ... + 35353.

It is an arithmetic number, because the mean of its divisors is an integer number (10761975).

Almost surely, 2^81243181 is an apocalyptic number.

It is an amenable number.

81243181 is a deficient number, since it is larger than the sum of its proper divisors (4852619).

81243181 is a wasteful number, since it uses less digits than its factorization.

81243181 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 68399.

The product of its digits is 1536, while the sum is 28.

The square root of 81243181 is about 9013.4999306596. The cubic root of 81243181 is about 433.1074356454.

Adding to 81243181 its reverse (18134218), we get a palindrome (99377399).

The spelling of 81243181 in words is "eighty-one million, two hundred forty-three thousand, one hundred eighty-one".