661717 has 4 divisors (see below), whose sum is σ = 756256. Its totient is φ = 567180.

The previous prime is 661697. The next prime is 661721. The reversal of 661717 is 717166.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 661717 - 2¹¹ = 659669 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661777) 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, 47259 + ... + 47272.

It is an arithmetic number, because the mean of its divisors is an integer number (189064).

2⁶⁶¹⁷¹⁷ is an apocalyptic number.

It is an amenable number.

661717 is a deficient number, since it is larger than the sum of its proper divisors (94539).

661717 is an equidigital number, since it uses as much as digits as its factorization.

661717 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 94538.

The product of its digits is 1764, while the sum is 28.

The square root of 661717 is about 813.4598945246. The cubic root of 661717 is about 87.1413125998.

It can be divided in two parts, 661 and 717, that added together give a triangular number (1378 = T₅₂).

The spelling of 661717 in words is "six hundred sixty-one thousand, seven hundred seventeen".