861396443721 has 24 divisors (see below), whose sum is σ = 1357617930240. Its totient is φ = 521956159200.

The previous prime is 861396443711. The next prime is 861396443741. The reversal of 861396443721 is 127344693168.

861396443721 is a `hidden beast` number, since 86 + 13 + 96 + 443 + 7 + 21 = 666.

It is not a de Polignac number, because 861396443721 - 2¹⁷ = 861396312649 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (861396443711) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 343090 + ... + 1356651.

It is an arithmetic number, because the mean of its divisors is an integer number (56567413760).

Almost surely, 2^861396443721 is an apocalyptic number.

It is an amenable number.

861396443721 is a deficient number, since it is larger than the sum of its proper divisors (496221486519).

861396443721 is a wasteful number, since it uses less digits than its factorization.

861396443721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1704877 (or 1704874 counting only the distinct ones).

The product of its digits is 5225472, while the sum is 54.

The spelling of 861396443721 in words is "eight hundred sixty-one billion, three hundred ninety-six million, four hundred forty-three thousand, seven hundred twenty-one".