81061961760 has 1152 divisors, whose sum is σ = 340259512320. Its totient is φ = 18032357376.

The previous prime is 81061961707. The next prime is 81061961797. The reversal of 81061961760 is 6716916018.

81061961760 is a `hidden beast` number, since 8 + 10 + 6 + 19 + 617 + 6 + 0 = 666.

It is a hoax number, since the sum of its digits (45) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (45).

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 191 ways as a sum of consecutive naturals, for example, 220877097 + ... + 220877463.

It is an arithmetic number, because the mean of its divisors is an integer number (295364160).

Almost surely, 2^81061961760 is an apocalyptic number.

81061961760 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 81061961760, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (170129756160).

81061961760 is an abundant number, since it is smaller than the sum of its proper divisors (259197550560).

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

81061961760 is a wasteful number, since it uses less digits than its factorization.

81061961760 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 452 (or 432 counting only the distinct ones).

The product of its (nonzero) digits is 108864, while the sum is 45.

The spelling of 81061961760 in words is "eighty-one billion, sixty-one million, nine hundred sixty-one thousand, seven hundred sixty".