861640 has 32 divisors (see below), whose sum is σ = 2089080. Its totient is φ = 317952.

The previous prime is 861617. The next prime is 861647. The reversal of 861640 is 46168.

It can be written as a sum of positive squares in 4 ways, for example, as 459684 + 401956 = 678^2 + 634^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (861647) 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, 309 + ... + 1348.

2⁸⁶¹⁶⁴⁰ is an apocalyptic number.

It is an amenable number.

861640 is an abundant number, since it is smaller than the sum of its proper divisors (1227440).

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

861640 is a wasteful number, since it uses less digits than its factorization.

861640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1681 (or 1677 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 25.

The square root of 861640 is about 928.2456571404. The cubic root of 861640 is about 95.1572649093.

The spelling of 861640 in words is "eight hundred sixty-one thousand, six hundred forty".