312721 has 8 divisors (see below), whose sum is σ = 334400. Its totient is φ = 291600.

The previous prime is 312709. The next prime is 312727. The reversal of 312721 is 127213.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a 6-Lehmer number, since φ(312721) divides (312721-1)⁶.

It is a cyclic number.

It is not a de Polignac number, because 312721 - 2⁹ = 312209 is a prime.

312721 is a lucky number.

It is a junction number, because it is equal to n+sod(n) for n = 312695 and 312704.

It is not an unprimeable number, because it can be changed into a prime (312727) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1996 + ... + 2146.

It is an arithmetic number, because the mean of its divisors is an integer number (41800).

2³¹²⁷²¹ is an apocalyptic number.

It is an amenable number.

312721 is a deficient number, since it is larger than the sum of its proper divisors (21679).

312721 is a wasteful number, since it uses less digits than its factorization.

312721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 279.

The product of its digits is 84, while the sum is 16.

The square root of 312721 is about 559.2146278487. The cubic root of 312721 is about 67.8764336132.

Adding to 312721 its reverse (127213), we get a palindrome (439934).

The spelling of 312721 in words is "three hundred twelve thousand, seven hundred twenty-one", and thus it is an iban number.