306721 has 4 divisors (see below), whose sum is σ = 314244. Its totient is φ = 299200.

The previous prime is 306707. The next prime is 306727. The reversal of 306721 is 127603.

306721 is nontrivially palindromic in base 7.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 127603 = 7 ⋅18229.

It can be written as a sum of positive squares in 2 ways, for example, as 130321 + 176400 = 361^2 + 420^2 .

It is a cyclic number.

It is not a de Polignac number, because 306721 - 2⁵ = 306689 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (306727) 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, 3700 + ... + 3781.

It is an arithmetic number, because the mean of its divisors is an integer number (78561).

2³⁰⁶⁷²¹ is an apocalyptic number.

It is an amenable number.

306721 is a deficient number, since it is larger than the sum of its proper divisors (7523).

306721 is an equidigital number, since it uses as much as digits as its factorization.

306721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7522.

The product of its (nonzero) digits is 252, while the sum is 19.

The square root of 306721 is about 553.8239792569. The cubic root of 306721 is about 67.4395251678.

The spelling of 306721 in words is "three hundred six thousand, seven hundred twenty-one".