661306 has 4 divisors (see below), whose sum is σ = 991962. Its totient is φ = 330652.

The previous prime is 661267. The next prime is 661321. The reversal of 661306 is 603166.

661306 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, and also an emirpimes, since its reverse is a distinct semiprime: 603166 = 2 ⋅301583.

It can be written as a sum of positive squares in only one way, i.e., 549081 + 112225 = 741^2 + 335^2 .

It is a Smith number, since the sum of its digits (22) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 165325 + ... + 165328.

2⁶⁶¹³⁰⁶ is an apocalyptic number.

661306 is a deficient number, since it is larger than the sum of its proper divisors (330656).

661306 is a wasteful number, since it uses less digits than its factorization.

661306 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 330655.

The product of its (nonzero) digits is 648, while the sum is 22.

The square root of 661306 is about 813.2072306614. The cubic root of 661306 is about 87.1232673745.

The spelling of 661306 in words is "six hundred sixty-one thousand, three hundred six".