7813 has 4 divisors (see below), whose sum is σ = 8428. Its totient is φ = 7200.

The previous prime is 7793. The next prime is 7817. The reversal of 7813 is 3187.

7813 = 62² + 63².

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 3844 + 3969 = 62^2 + 63^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-7813 is a prime.

It is a super-2 number, since 2×7813² = 122085938, which contains 22 as substring.

It is a Duffinian number.

7813 is a lucky number.

It is a plaindrome in base 5 and base 15.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (7817) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 288 + ... + 313.

It is an arithmetic number, because the mean of its divisors is an integer number (2107).

2⁷⁸¹³ is an apocalyptic number.

7813 is the 63-rd centered square number.

It is an amenable number.

7813 is a deficient number, since it is larger than the sum of its proper divisors (615).

7813 is a wasteful number, since it uses less digits than its factorization.

7813 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 614.

The product of its digits is 168, while the sum is 19.

The square root of 7813 is about 88.3911760302. The cubic root of 7813 is about 19.8429364475.

It can be divided in two parts, 781 and 3, that added together give a square (784 = 28²).

The spelling of 7813 in words is "seven thousand, eight hundred thirteen".