81935510912640 has 1536 divisors, whose sum is σ = 368490635735040. Its totient is φ = 16900948131840.

The previous prime is 81935510912579. The next prime is 81935510912683. The reversal of 81935510912640 is 4621901553918.

81935510912640 is a `hidden beast` number, since 8 + 1 + 9 + 35 + 510 + 91 + 2 + 6 + 4 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is an unprimeable number.

It is a polite number, since it can be written in 191 ways as a sum of consecutive naturals, for example, 1640555509 + ... + 1640605451.

It is an arithmetic number, because the mean of its divisors is an integer number (239902757640).

Almost surely, 2^{81935510912640} is an apocalyptic number.

81935510912640 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 81935510912640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (184245317867520).

81935510912640 is an abundant number, since it is smaller than the sum of its proper divisors (286555124822400).

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

81935510912640 is a wasteful number, since it uses less digits than its factorization.

81935510912640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 50132 (or 50108 counting only the distinct ones).

The product of its (nonzero) digits is 2332800, while the sum is 54.

The spelling of 81935510912640 in words is "eighty-one trillion, nine hundred thirty-five billion, five hundred ten million, nine hundred twelve thousand, six hundred forty".