1000000081 has 4 divisors (see below), whose sum is σ = 1000064164. Its totient is φ = 999936000.

The previous prime is 1000000033. The next prime is 1000000087. The reversal of 1000000081 is 1800000001.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 368985681 + 631014400 = 19209^2 + 25120^2 .

It is a cyclic number.

It is not a de Polignac number, because 1000000081 - 2²¹ = 997902929 is a prime.

It is a super-2 number, since 2×1000000081² = 2000000324000013122, which contains 22 as substring.

It is a Duffinian number.

1000000081 is a modest number, since divided by 81 gives 1 as remainder.

It is not an unprimeable number, because it can be changed into a prime (1000000087) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8281 + ... + 45481.

It is an arithmetic number, because the mean of its divisors is an integer number (250016041).

Almost surely, 2^1000000081 is an apocalyptic number.

It is an amenable number.

1000000081 is a deficient number, since it is larger than the sum of its proper divisors (64083).

1000000081 is an equidigital number, since it uses as much as digits as its factorization.

1000000081 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 64082.

The product of its (nonzero) digits is 8, while the sum is 10.

The square root of 1000000081 is about 31622.7778824062. Note that the first 3 decimals coincide. The cubic root of 1000000081 is about 1000.0000270000. Note that the first 4 decimals are identical.

Adding to 1000000081 its reverse (1800000001), we get a palindrome (2800000082).

The spelling of 1000000081 in words is "one billion, eighty-one", and thus it is an aban number and an uban number.