81696522240 has 648 divisors, whose sum is σ = 309569911560. Its totient is φ = 20639121408.

The previous prime is 81696522211. The next prime is 81696522251. The reversal of 81696522240 is 4222569618.

81696522240 is a `hidden beast` number, since 8 + 16 + 96 + 522 + 24 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (648).

It is a super-2 number, since 2×81696522240² (a number of 23 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 4299816951 + ... + 4299816969.

It is an arithmetic number, because the mean of its divisors is an integer number (477731345).

Almost surely, 2^81696522240 is an apocalyptic number.

81696522240 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 81696522240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (154784955780).

81696522240 is an abundant number, since it is smaller than the sum of its proper divisors (227873389320).

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

81696522240 is an frugal number, since it uses more digits than its factorization.

81696522240 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 82 (or 29 counting only the distinct ones).

The product of its (nonzero) digits is 414720, while the sum is 45.

The spelling of 81696522240 in words is "eighty-one billion, six hundred ninety-six million, five hundred twenty-two thousand, two hundred forty".