861999444 has 18 divisors (see below), whose sum is σ = 2178943130. Its totient is φ = 287333136.

The previous prime is 861999431. The next prime is 861999449. The reversal of 861999444 is 444999168.

It is a happy number.

861999444 is a `hidden beast` number, since 8 + 6 + 199 + 9 + 444 = 666.

It can be written as a sum of positive squares in only one way, i.e., 853808400 + 8191044 = 29220^2 + 2862^2 .

It is a tau number, because it is divible by the number of its divisors (18).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (861999449) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 11972179 + ... + 11972250.

Almost surely, 2^861999444 is an apocalyptic number.

It is an amenable number.

861999444 is an abundant number, since it is smaller than the sum of its proper divisors (1316943686).

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

861999444 is a wasteful number, since it uses less digits than its factorization.

861999444 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23944439 (or 23944434 counting only the distinct ones).

The product of its digits is 2239488, while the sum is 54.

The square root of 861999444 is about 29359.8270430873. The cubic root of 861999444 is about 951.7049508772.

The spelling of 861999444 in words is "eight hundred sixty-one million, nine hundred ninety-nine thousand, four hundred forty-four".