81212503680 has 768 divisors, whose sum is σ = 354697574400. Its totient is φ = 16631193600.

The previous prime is 81212503679. The next prime is 81212503703. The reversal of 81212503680 is 8630521218.

It is a happy number.

81212503680 is a `hidden beast` number, since 81 + 2 + 12 + 503 + 68 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 31488631 + ... + 31491209.

It is an arithmetic number, because the mean of its divisors is an integer number (461845800).

Almost surely, 2^81212503680 is an apocalyptic number.

81212503680 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 81212503680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (177348787200).

81212503680 is an abundant number, since it is smaller than the sum of its proper divisors (273485070720).

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

81212503680 is a wasteful number, since it uses less digits than its factorization.

81212503680 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2693 (or 2678 counting only the distinct ones).

The product of its (nonzero) digits is 23040, while the sum is 36.

The spelling of 81212503680 in words is "eighty-one billion, two hundred twelve million, five hundred three thousand, six hundred eighty".