7940 has 12 divisors (see below), whose sum is σ = 16716. Its totient is φ = 3168.

The previous prime is 7937. The next prime is 7949. The reversal of 7940 is 497.

7940 = T₆₁ + T₆₂ + ... + T₆₄.

It can be written as a sum of positive squares in 2 ways, for example, as 4096 + 3844 = 64^2 + 62^2 .

It is a Harshad number since it is a multiple of its sum of digits (20), and also a Moran number because the ratio is a prime number: 397 = 7940 / (7 + 9 + 4 + 0).

It is not an unprimeable number, because it can be changed into a prime (7949) 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, 179 + ... + 218.

It is an arithmetic number, because the mean of its divisors is an integer number (1393).

2⁷⁹⁴⁰ is an apocalyptic number.

It is an amenable number.

7940 is an abundant number, since it is smaller than the sum of its proper divisors (8776).

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

It is a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (8358).

7940 is a wasteful number, since it uses less digits than its factorization.

7940 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 406 (or 404 counting only the distinct ones).

The product of its (nonzero) digits is 252, while the sum is 20.

The square root of 7940 is about 89.1066776398. The cubic root of 7940 is about 19.9498744765.

Adding to 7940 its product of nonzero digits (252), we get a 13-th power (8192 = 2¹³).

It can be divided in two parts, 79 and 40, that multiplied together give a triangular number (3160 = T₇₉).

The spelling of 7940 in words is "seven thousand, nine hundred forty".