81731962520 has 384 divisors, whose sum is σ = 215335895040. Its totient is φ = 27851765760.

The previous prime is 81731962513. The next prime is 81731962567. The reversal of 81731962520 is 2526913718.

It is a super-2 number, since 2×81731962520² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 643558697 + ... + 643558823.

It is an arithmetic number, because the mean of its divisors is an integer number (560770560).

Almost surely, 2^81731962520 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81731962520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (107667947520).

81731962520 is an abundant number, since it is smaller than the sum of its proper divisors (133603932520).

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

81731962520 is a wasteful number, since it uses less digits than its factorization.

81731962520 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 315 (or 298 counting only the distinct ones).

The product of its (nonzero) digits is 181440, while the sum is 44.

The spelling of 81731962520 in words is "eighty-one billion, seven hundred thirty-one million, nine hundred sixty-two thousand, five hundred twenty".