81572026316778 has 48 divisors (see below), whose sum is σ = 188731718323200. Its totient is φ = 25406192841120.

The previous prime is 81572026316773. The next prime is 81572026316801. The reversal of 81572026316778 is 87761362027518.

It is a happy number.

81572026316778 is a `hidden beast` number, since 8 + 1 + 572 + 0 + 26 + 31 + 6 + 7 + 7 + 8 = 666.

81572026316778 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (81572026316773) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 2520439458 + ... + 2520471821.

It is an arithmetic number, because the mean of its divisors is an integer number (3931910798400).

Almost surely, 2^{81572026316778} is an apocalyptic number.

81572026316778 is an abundant number, since it is smaller than the sum of its proper divisors (107159692006422).

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

81572026316778 is a wasteful number, since it uses less digits than its factorization.

81572026316778 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5040911347 (or 5040911344 counting only the distinct ones).

The product of its (nonzero) digits is 47416320, while the sum is 63.

The spelling of 81572026316778 in words is "eighty-one trillion, five hundred seventy-two billion, twenty-six million, three hundred sixteen thousand, seven hundred seventy-eight".