805661 has 4 divisors (see below), whose sum is σ = 810492. Its totient is φ = 800832.

The previous prime is 805639. The next prime is 805687. The reversal of 805661 is 166508.

805661 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 422500 + 383161 = 650^2 + 619^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-805661 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 805661.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (805061) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2156 + ... + 2501.

It is an arithmetic number, because the mean of its divisors is an integer number (202623).

2⁸⁰⁵⁶⁶¹ is an apocalyptic number.

It is an amenable number.

805661 is a deficient number, since it is larger than the sum of its proper divisors (4831).

805661 is a wasteful number, since it uses less digits than its factorization.

805661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4830.

The product of its (nonzero) digits is 1440, while the sum is 26.

The square root of 805661 is about 897.5862075589. The cubic root of 805661 is about 93.0502291581.

The spelling of 805661 in words is "eight hundred five thousand, six hundred sixty-one".