81355778010 has 96 divisors (see below), whose sum is σ = 228098012688. Its totient is φ = 19999503360.

The previous prime is 81355777967. The next prime is 81355778113. The reversal of 81355778010 is 1087755318.

81355778010 is a `hidden beast` number, since 8 + 1 + 3 + 557 + 7 + 80 + 10 = 666.

It can be written as a sum of positive squares in 8 ways, for example, as 18820272969 + 62535505041 = 137187^2 + 250071^2 .

It is a super-2 number, since 2×81355778010² (a number of 23 digits) contains 22 as substring.

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

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 844684 + ... + 936056.

Almost surely, 2^81355778010 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81355778010, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (114049006344).

81355778010 is an abundant number, since it is smaller than the sum of its proper divisors (146742234678).

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

81355778010 is a wasteful number, since it uses less digits than its factorization.

81355778010 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 92160 (or 92157 counting only the distinct ones).

The product of its (nonzero) digits is 235200, while the sum is 45.

The spelling of 81355778010 in words is "eighty-one billion, three hundred fifty-five million, seven hundred seventy-eight thousand, ten".