81908962560 has 432 divisors, whose sum is σ = 298112330880. Its totient is φ = 21528944640.

The previous prime is 81908962549. The next prime is 81908962621. The reversal of 81908962560 is 6526980918.

It is a happy number.

81908962560 is a `hidden beast` number, since 8 + 1 + 9 + 0 + 8 + 9 + 625 + 6 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (432).

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a junction number, because it is equal to n+sod(n) for n = 81908962497 and 81908962506.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 22081986 + ... + 22085694.

It is an arithmetic number, because the mean of its divisors is an integer number (690074840).

Almost surely, 2^81908962560 is an apocalyptic number.

81908962560 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 81908962560, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (149056165440).

81908962560 is an abundant number, since it is smaller than the sum of its proper divisors (216203368320).

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

81908962560 is an equidigital number, since it uses as much as digits as its factorization.

81908962560 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3816 (or 3790 counting only the distinct ones).

The product of its (nonzero) digits is 1866240, while the sum is 54.

The spelling of 81908962560 in words is "eighty-one billion, nine hundred eight million, nine hundred sixty-two thousand, five hundred sixty".