81707781120 has 352 divisors, whose sum is σ = 301002932736. Its totient is φ = 18530304000.

The previous prime is 81707781119. The next prime is 81707781131. The reversal of 81707781120 is 2118770718.

It is a super-2 number, since 2×81707781120² (a number of 23 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 14082220 + ... + 14088020.

It is an arithmetic number, because the mean of its divisors is an integer number (855121968).

Almost surely, 2^81707781120 is an apocalyptic number.

81707781120 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 81707781120, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (150501466368).

81707781120 is an abundant number, since it is smaller than the sum of its proper divisors (219295151616).

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

81707781120 is a wasteful number, since it uses less digits than its factorization.

81707781120 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5967 (or 5949 counting only the distinct ones).

The product of its (nonzero) digits is 43904, while the sum is 42.

The spelling of 81707781120 in words is "eighty-one billion, seven hundred seven million, seven hundred eighty-one thousand, one hundred twenty".