661705 has 16 divisors (see below), whose sum is σ = 886464. Its totient is φ = 470080.

The previous prime is 661697. The next prime is 661721. The reversal of 661705 is 507166.

It is not a de Polignac number, because 661705 - 2³ = 661697 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 661705.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2802 + ... + 3028.

It is an arithmetic number, because the mean of its divisors is an integer number (55404).

2⁶⁶¹⁷⁰⁵ is an apocalyptic number.

It is an amenable number.

661705 is a deficient number, since it is larger than the sum of its proper divisors (224759).

661705 is a wasteful number, since it uses less digits than its factorization.

661705 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 296.

The product of its (nonzero) digits is 1260, while the sum is 25.

The square root of 661705 is about 813.4525185897. The cubic root of 661705 is about 87.1407858378.

It can be divided in two parts, 66 and 1705, that added together give a palindrome (1771).

The spelling of 661705 in words is "six hundred sixty-one thousand, seven hundred five".