81801081 has 24 divisors (see below), whose sum is σ = 121205760. Its totient is φ = 53143776.

The previous prime is 81801077. The next prime is 81801107. The reversal of 81801081 is 18010818.

It is not a de Polignac number, because 81801081 - 2² = 81801077 is a prime.

It is a super-2 number, since 2×81801081² = 13382833705537122, which contains 22 as substring.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (81801001) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 66831 + ... + 68043.

It is an arithmetic number, because the mean of its divisors is an integer number (5050240).

Almost surely, 2^81801081 is an apocalyptic number.

It is an amenable number.

81801081 is a deficient number, since it is larger than the sum of its proper divisors (39404679).

81801081 is a wasteful number, since it uses less digits than its factorization.

81801081 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1405 (or 1402 counting only the distinct ones).

The product of its (nonzero) digits is 512, while the sum is 27.

The square root of 81801081 is about 9044.3950046424. The cubic root of 81801081 is about 434.0965633492.

Adding to 81801081 its reverse (18010818), we get a palindrome (99811899).

It can be divided in two parts, 8180 and 1081, that added together give a cube (9261 = 21³).

The spelling of 81801081 in words is "eighty-one million, eight hundred one thousand, eighty-one".