81697988612240 has 480 divisors, whose sum is σ = 256509165505536. Its totient is φ = 23498821232640.

The previous prime is 81697988612239. The next prime is 81697988612243. The reversal of 81697988612240 is 4221688979618.

It is a super-2 number, since 2×81697988612240² (a number of 29 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (81697988612243) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 4542048527 + ... + 4542066513.

Almost surely, 2^{81697988612240} is an apocalyptic number.

81697988612240 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81697988612240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (128254582752768).

81697988612240 is an abundant number, since it is smaller than the sum of its proper divisors (174811176893296).

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

81697988612240 is a wasteful number, since it uses less digits than its factorization.

81697988612240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22407 (or 22388 counting only the distinct ones).

The product of its (nonzero) digits is 167215104, while the sum is 71.

The spelling of 81697988612240 in words is "eighty-one trillion, six hundred ninety-seven billion, nine hundred eighty-eight million, six hundred twelve thousand, two hundred forty".