81000810 has 80 divisors (see below), whose sum is σ = 237628512. Its totient is φ = 19634400.

The previous prime is 81000809. The next prime is 81000841. The reversal of 81000810 is 1800018.

It is a happy number.

It is a super-2 number, since 2×81000810² = 13122262441312200, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is an unprimeable number.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 4365 + ... + 13455.

Almost surely, 2^81000810 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81000810, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (118814256).

81000810 is an abundant number, since it is smaller than the sum of its proper divisors (156627702).

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

81000810 is a wasteful number, since it uses less digits than its factorization.

81000810 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9121 (or 9112 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 18.

The square root of 81000810 is about 9000.0449998875. The cubic root of 81000810 is about 432.6763133370.

Adding to 81000810 its reverse (1800018), we get a palindrome (82800828).

81000810 divided by its reverse (1800018) gives a triangular number (45 = T₉).

It can be divided in two parts, 810008 and 10, that added together give a palindrome (810018).

The spelling of 81000810 in words is "eighty-one million, eight hundred ten", and thus it is an aban number.