861534819720 has 768 divisors, whose sum is σ = 3162032640000. Its totient is φ = 202412390400.

The previous prime is 861534819671. The next prime is 861534819731. The reversal of 861534819720 is 27918435168.

861534819720 is a `hidden beast` number, since 8 + 6 + 1 + 53 + 481 + 97 + 20 = 666.

It is a Cunningham number, because it is equal to 928189²-1.

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, 937469421 + ... + 937470339.

It is an arithmetic number, because the mean of its divisors is an integer number (4117230000).

It is a 1-persistent number, because it is pandigital, but 2⋅861534819720 = 1723069639440 is not.

Almost surely, 2^861534819720 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 861534819720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1581016320000).

861534819720 is an abundant number, since it is smaller than the sum of its proper divisors (2300497820280).

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

861534819720 is a wasteful number, since it uses less digits than its factorization.

861534819720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1138 (or 1131 counting only the distinct ones).

The product of its (nonzero) digits is 2903040, while the sum is 54.

The spelling of 861534819720 in words is "eight hundred sixty-one billion, five hundred thirty-four million, eight hundred nineteen thousand, seven hundred twenty".