861949861 has 8 divisors (see below), whose sum is σ = 944124120. Its totient is φ = 783272448.

The previous prime is 861949853. The next prime is 861949867. The reversal of 861949861 is 168949168.

861949861 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 4 ways, for example, as 425390625 + 436559236 = 20625^2 + 20894^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 861949861 - 2³ = 861949853 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 861949799 and 861949808.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (861949867) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 873696 + ... + 874681.

It is an arithmetic number, because the mean of its divisors is an integer number (118015515).

Almost surely, 2^861949861 is an apocalyptic number.

It is an amenable number.

861949861 is a deficient number, since it is larger than the sum of its proper divisors (82174259).

861949861 is a wasteful number, since it uses less digits than its factorization.

861949861 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1748423.

The product of its digits is 746496, while the sum is 52.

The square root of 861949861 is about 29358.9826288310. The cubic root of 861949861 is about 951.6867028796.

The spelling of 861949861 in words is "eight hundred sixty-one million, nine hundred forty-nine thousand, eight hundred sixty-one".