861687 has 12 divisors (see below), whose sum is σ = 1264120. Its totient is φ = 565488.

The previous prime is 861659. The next prime is 861691. The reversal of 861687 is 786168.

It is not a de Polignac number, because 861687 - 2⁷ = 861559 is a prime.

It is a Duffinian number.

861687 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (861617) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 112 + ... + 1317.

2⁸⁶¹⁶⁸⁷ is an apocalyptic number.

861687 is a deficient number, since it is larger than the sum of its proper divisors (402433).

861687 is a wasteful number, since it uses less digits than its factorization.

861687 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1502 (or 1499 counting only the distinct ones).

The product of its digits is 16128, while the sum is 36.

The square root of 861687 is about 928.2709733693. The cubic root of 861687 is about 95.1589950635.

The spelling of 861687 in words is "eight hundred sixty-one thousand, six hundred eighty-seven".