81081020 has 24 divisors (see below), whose sum is σ = 170440368. Its totient is φ = 32400000.

The previous prime is 81081019. The next prime is 81081029. The reversal of 81081020 is 2018018.

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a junction number, because it is equal to n+sod(n) for n = 81080983 and 81081001.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81081029) 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, 34895 + ... + 37145.

It is an arithmetic number, because the mean of its divisors is an integer number (7101682).

Almost surely, 2^81081020 is an apocalyptic number.

It is a pronic number, being equal to 9004×9005.

It is an amenable number.

81081020 is an abundant number, since it is smaller than the sum of its proper divisors (89359348).

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

81081020 is a wasteful number, since it uses less digits than its factorization.

81081020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4061 (or 4059 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 20.

The square root of 81081020 is about 9004.4999861181. The cubic root of 81081020 is about 432.8190835883.

Adding to 81081020 its reverse (2018018), we get a palindrome (83099038).

The spelling of 81081020 in words is "eighty-one million, eighty-one thousand, twenty".