81697494816 has 288 divisors, whose sum is σ = 280580751360. Its totient is φ = 22043653632.

The previous prime is 81697494733. The next prime is 81697494841. The reversal of 81697494816 is 61849479618.

81697494816 is a `hidden beast` number, since 8 + 1 + 69 + 7 + 494 + 81 + 6 = 666.

It is a tau number, because it is divible by the number of its divisors (288).

It is a Harshad number since it is a multiple of its sum of digits (63).

It is a nude number because it is divisible by every one of its digits.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 3651921 + ... + 3674223.

It is an arithmetic number, because the mean of its divisors is an integer number (974238720).

Almost surely, 2^81697494816 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81697494816, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (140290375680).

81697494816 is an abundant number, since it is smaller than the sum of its proper divisors (198883256544).

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

81697494816 is a wasteful number, since it uses less digits than its factorization.

81697494816 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22428 (or 22417 counting only the distinct ones).

The product of its digits is 20901888, while the sum is 63.

The spelling of 81697494816 in words is "eighty-one billion, six hundred ninety-seven million, four hundred ninety-four thousand, eight hundred sixteen".