312661 has 4 divisors (see below), whose sum is σ = 316512. Its totient is φ = 308812.

The previous prime is 312643. The next prime is 312673. The reversal of 312661 is 166213.

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, and also an emirpimes, since its reverse is a distinct semiprime: 166213 = 347 ⋅479.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-312661 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 (312601) 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, 1801 + ... + 1966.

It is an arithmetic number, because the mean of its divisors is an integer number (79128).

2³¹²⁶⁶¹ is an apocalyptic number.

It is an amenable number.

312661 is a deficient number, since it is larger than the sum of its proper divisors (3851).

312661 is an equidigital number, since it uses as much as digits as its factorization.

312661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3850.

The product of its digits is 216, while the sum is 19.

The square root of 312661 is about 559.1609786099. The cubic root of 312661 is about 67.8720923137.

Subtracting from 312661 its product of digits (216), we obtain a triangular number (312445 = T₇₉₀).

Adding to 312661 its reverse (166213), we get a palindrome (478874).

The spelling of 312661 in words is "three hundred twelve thousand, six hundred sixty-one".