861994539912 has 128 divisors (see below), whose sum is σ = 2367922636800. Its totient is φ = 259320576000.

The previous prime is 861994539893. The next prime is 861994539979. The reversal of 861994539912 is 219935499168.

It is a Harshad number since it is a multiple of its sum of digits (66).

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, 75297373 + ... + 75308819.

It is an arithmetic number, because the mean of its divisors is an integer number (18499395600).

Almost surely, 2^861994539912 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 861994539912, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1183961318400).

861994539912 is an abundant number, since it is smaller than the sum of its proper divisors (1505928096888).

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

861994539912 is a wasteful number, since it uses less digits than its factorization.

861994539912 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13507 (or 13503 counting only the distinct ones).

The product of its digits is 37791360, while the sum is 66.

The spelling of 861994539912 in words is "eight hundred sixty-one billion, nine hundred ninety-four million, five hundred thirty-nine thousand, nine hundred twelve".