81302209920 has 512 divisors, whose sum is σ = 313588800000. Its totient is φ = 19828924416.

The previous prime is 81302209913. The next prime is 81302209921. The reversal of 81302209920 is 2990220318.

It is a super-2 number, since 2×81302209920² (a number of 23 digits) contains 22 as substring.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81302209921) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 9517011 + ... + 9525549.

It is an arithmetic number, because the mean of its divisors is an integer number (612478125).

Almost surely, 2^81302209920 is an apocalyptic number.

81302209920 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 81302209920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (156794400000).

81302209920 is an abundant number, since it is smaller than the sum of its proper divisors (232286590080).

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

81302209920 is a wasteful number, since it uses less digits than its factorization.

81302209920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8615 (or 8597 counting only the distinct ones).

The product of its (nonzero) digits is 15552, while the sum is 36.

The spelling of 81302209920 in words is "eighty-one billion, three hundred two million, two hundred nine thousand, nine hundred twenty".