7820 has 24 divisors (see below), whose sum is σ = 18144. Its totient is φ = 2816.

The previous prime is 7817. The next prime is 7823. The reversal of 7820 is 287.

It is an interprime number because it is at equal distance from previous prime (7817) and next prime (7823).

It is a super-2 number, since 2×7820² = 122304800, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (17).

It is an Ulam number.

7820 is an undulating number in base 13.

It is not an unprimeable number, because it can be changed into a prime (7823) 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 7 ways as a sum of consecutive naturals, for example, 329 + ... + 351.

It is an arithmetic number, because the mean of its divisors is an integer number (756).

2⁷⁸²⁰ is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 7820, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (9072).

7820 is an abundant number, since it is smaller than the sum of its proper divisors (10324).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

7820 is a wasteful number, since it uses less digits than its factorization.

7820 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 49 (or 47 counting only the distinct ones).

The product of its (nonzero) digits is 112, while the sum is 17.

The square root of 7820 is about 88.4307638777. The cubic root of 7820 is about 19.8488607230.

The spelling of 7820 in words is "seven thousand, eight hundred twenty".