861556 has 6 divisors (see below), whose sum is σ = 1507730. Its totient is φ = 430776.

The previous prime is 861551. The next prime is 861559. The reversal of 861556 is 655168.

861556 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 only one way, i.e., 839056 + 22500 = 916^2 + 150^2 .

It is a super-2 number, since 2×861556² = 1484557482272, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (861551) by changing a digit.

861556 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 107691 + ... + 107698.

2⁸⁶¹⁵⁵⁶ is an apocalyptic number.

It is an amenable number.

861556 is a deficient number, since it is larger than the sum of its proper divisors (646174).

861556 is a wasteful number, since it uses less digits than its factorization.

861556 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 215393 (or 215391 counting only the distinct ones).

The product of its digits is 7200, while the sum is 31.

The square root of 861556 is about 928.2004093944. The cubic root of 861556 is about 95.1541725621.

The spelling of 861556 in words is "eight hundred sixty-one thousand, five hundred fifty-six".