81020498881 has 45 divisors (see below), whose sum is σ = 97764560649. Its totient is φ = 67138841952.

The previous prime is 81020498869. The next prime is 81020498939. The reversal of 81020498881 is 18889402018.

The square root of 81020498881 is 284641.

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

It can be written as a sum of positive squares in 4 ways, for example, as 4645649281 + 76374849600 = 68159^2 + 276360^2 .

It is not a de Polignac number, because 81020498881 - 2⁹ = 81020498369 is a prime.

It is a super-2 number, since 2×81020498881² (a number of 23 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (49).

It is not an unprimeable number, because it can be changed into a prime (81020498281) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 44 ways as a sum of consecutive naturals, for example, 516054055 + ... + 516054211.

Almost surely, 2^81020498881 is an apocalyptic number.

81020498881 is the 284641-st square number.

81020498881 is the 142321-st centered octagonal number.

It is an amenable number.

81020498881 is a deficient number, since it is larger than the sum of its proper divisors (16744061768).

81020498881 is an frugal number, since it uses more digits than its factorization.

81020498881 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 416 (or 201 counting only the distinct ones).

The product of its (nonzero) digits is 294912, while the sum is 49.

Multiplying 81020498881 by its sum of digits (49), we get a square (3970004445169 = 1992487²).

81020498881 divided by its sum of digits (49) gives a square (1653479569 = 40663²).

The spelling of 81020498881 in words is "eighty-one billion, twenty million, four hundred ninety-eight thousand, eight hundred eighty-one".