81957521378304 has 3168 divisors, whose sum is σ = 313161918189120. Its totient is φ = 21189497978880.

The previous prime is 81957521378281. The next prime is 81957521378311. The reversal of 81957521378304 is 40387312575918.

It is a happy number.

81957521378304 is a `hidden beast` number, since 8 + 1 + 9 + 5 + 7 + 521 + 3 + 78 + 30 + 4 = 666.

It is a tau number, because it is divible by the number of its divisors (3168).

It is an unprimeable number.

It is a polite number, since it can be written in 287 ways as a sum of consecutive naturals, for example, 725287799752 + ... + 725287799864.

It is an arithmetic number, because the mean of its divisors is an integer number (98851615590).

Almost surely, 2^{81957521378304} 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 81957521378304, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (156580959094560).

81957521378304 is an abundant number, since it is smaller than the sum of its proper divisors (231204396810816).

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

81957521378304 is a wasteful number, since it uses less digits than its factorization.

81957521378304 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 309 (or 268 counting only the distinct ones).

The product of its (nonzero) digits is 50803200, while the sum is 63.

The spelling of 81957521378304 in words is "eighty-one trillion, nine hundred fifty-seven billion, five hundred twenty-one million, three hundred seventy-eight thousand, three hundred four".