7817940 has 108 divisors (see below), whose sum is σ = 25778844. Its totient is φ = 1916928.

The previous prime is 7817939. The next prime is 7817941. The reversal of 7817940 is 497187.

It is an interprime number because it is at equal distance from previous prime (7817939) and next prime (7817941).

It can be written as a sum of positive squares in 6 ways, for example, as 133956 + 7683984 = 366^2 + 2772^2 .

It is a super-2 number, since 2×7817940² = 122240371687200, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 7817895 and 7817904.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (7817941) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 30292 + ... + 30548.

It is an arithmetic number, because the mean of its divisors is an integer number (238693).

Almost surely, 2^7817940 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 7817940, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (12889422).

7817940 is an abundant number, since it is smaller than the sum of its proper divisors (17960904).

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

7817940 is a wasteful number, since it uses less digits than its factorization.

7817940 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 298 (or 280 counting only the distinct ones).

The product of its (nonzero) digits is 14112, while the sum is 36.

The square root of 7817940 is about 2796.0579393138. The cubic root of 7817940 is about 198.4711766062.

The spelling of 7817940 in words is "seven million, eight hundred seventeen thousand, nine hundred forty".