81162081 has 135 divisors (see below), whose sum is σ = 167866083. Its totient is φ = 38918880.

The previous prime is 81162071. The next prime is 81162121. The reversal of 81162081 is 18026118.

The square root of 81162081 is 9009.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 12006225 + 69155856 = 3465^2 + 8316^2 .

It is not a de Polignac number, because 81162081 - 2⁹ = 81161569 is a prime.

It is a super-2 number, since 2×81162081² = 13174566784501122, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is not an unprimeable number, because it can be changed into a prime (81162071) by changing a digit.

It is a polite number, since it can be written in 134 ways as a sum of consecutive naturals, for example, 6243231 + ... + 6243243.

Almost surely, 2^81162081 is an apocalyptic number.

81162081 is a gapful number since it is divisible by the number (81) formed by its first and last digit.

81162081 is the 9009-th square number.

81162081 is the 4505-th centered octagonal number.

It is an amenable number.

81162081 is an abundant number, since it is smaller than the sum of its proper divisors (86704002).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81162081 is a wasteful number, since it uses less digits than its factorization.

81162081 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 74 (or 34 counting only the distinct ones).

The product of its (nonzero) digits is 768, while the sum is 27.

The cubic root of 81162081 is about 432.9632729527.

81162081 divided by its sum of digits (27) gives a palindrome (3006003).

Adding to 81162081 its reverse (18026118), we get a palindrome (99188199).

The spelling of 81162081 in words is "eighty-one million, one hundred sixty-two thousand, eighty-one".