81350721792 has 576 divisors, whose sum is σ = 274650808320. Its totient is φ = 23600332800.

The previous prime is 81350721763. The next prime is 81350721833. The reversal of 81350721792 is 29712705318.

81350721792 is a `hidden beast` number, since 81 + 350 + 7 + 217 + 9 + 2 = 666.

It is a tau number, because it is divible by the number of its divisors (576).

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 83779867 + ... + 83780837.

It is an arithmetic number, because the mean of its divisors is an integer number (476824320).

Almost surely, 2^81350721792 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 81350721792, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (137325404160).

81350721792 is an abundant number, since it is smaller than the sum of its proper divisors (193300086528).

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

81350721792 is a wasteful number, since it uses less digits than its factorization.

81350721792 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1067 (or 1047 counting only the distinct ones).

The product of its (nonzero) digits is 211680, while the sum is 45.

The spelling of 81350721792 in words is "eighty-one billion, three hundred fifty million, seven hundred twenty-one thousand, seven hundred ninety-two".