81020 has 12 divisors (see below), whose sum is σ = 170184. Its totient is φ = 32400.

The previous prime is 81019. The next prime is 81023. The reversal of 81020 is 2018.

81020 = T₁₉ + T₂₀ + ... + T₇₈.

81020 = 24² + 25² + ... + 63².

It is a junction number, because it is equal to n+sod(n) for n = 80992 and 81010.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81023) 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, 2006 + ... + 2045.

It is an arithmetic number, because the mean of its divisors is an integer number (14182).

2⁸¹⁰²⁰ is an apocalyptic number.

It is an amenable number.

81020 is an abundant number, since it is smaller than the sum of its proper divisors (89164).

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

It is a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (85092).

81020 is a wasteful number, since it uses less digits than its factorization.

81020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4060 (or 4058 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 11.

The square root of 81020 is about 284.6401236650. The cubic root of 81020 is about 43.2710479262.

Adding to 81020 its reverse (2018), we get a palindrome (83038).

The spelling of 81020 in words is "eighty-one thousand, twenty".