81528655779684 has 135 divisors (see below), whose sum is σ = 216389466172803. Its totient is φ = 26767027778832.

The previous prime is 81528655779677. The next prime is 81528655779689. The reversal of 81528655779684 is 48697755682518.

The square root of 81528655779684 is 9029322.

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

81528655779684 is a `hidden beast` number, since 8 + 1 + 52 + 8 + 6 + 557 + 7 + 9 + 6 + 8 + 4 = 666.

It is a Harshad number since it is a multiple of its sum of digits (81).

It is not an unprimeable number, because it can be changed into a prime (81528655779689) by changing a digit.

It is a polite number, since it can be written in 44 ways as a sum of consecutive naturals, for example, 10889358589 + ... + 10889366075.

Almost surely, 2^{81528655779684} is an apocalyptic number.

81528655779684 is the 9029322-nd square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81528655779684

81528655779684 is an abundant number, since it is smaller than the sum of its proper divisors (134860810393119).

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

81528655779684 is an frugal number, since it uses more digits than its factorization.

81528655779684 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15124 (or 7559 counting only the distinct ones).

The product of its digits is 8128512000, while the sum is 81.

81528655779684 divided by its sum of digits (81) gives a square (1006526614564 = 1003258²).

The spelling of 81528655779684 in words is "eighty-one trillion, five hundred twenty-eight billion, six hundred fifty-five million, seven hundred seventy-nine thousand, six hundred eighty-four".