855661 has 4 divisors (see below), whose sum is σ = 906012. Its totient is φ = 805312.

The previous prime is 855641. The next prime is 855667. The reversal of 855661 is 166558.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 670761 + 184900 = 819^2 + 430^2 .

It is a cyclic number.

It is not a de Polignac number, because 855661 - 2¹⁵ = 822893 is a prime.

It is an Ulam number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (855667) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 25150 + ... + 25183.

It is an arithmetic number, because the mean of its divisors is an integer number (226503).

2⁸⁵⁵⁶⁶¹ is an apocalyptic number.

It is an amenable number.

855661 is a deficient number, since it is larger than the sum of its proper divisors (50351).

855661 is a wasteful number, since it uses less digits than its factorization.

855661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 50350.

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

The square root of 855661 is about 925.0194592548. The cubic root of 855661 is about 94.9366521353.

The spelling of 855661 in words is "eight hundred fifty-five thousand, six hundred sixty-one".