7890640 has 40 divisors (see below), whose sum is σ = 18701928. Its totient is φ = 3095040.

The previous prime is 7890611. The next prime is 7890661. The reversal of 7890640 is 460987.

It can be written as a sum of positive squares in 4 ways, for example, as 28224 + 7862416 = 168^2 + 2804^2 .

It is a tau number, because it is divible by the number of its divisors (40).

It is a junction number, because it is equal to n+sod(n) for n = 7890596 and 7890605.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3310 + ... + 5170.

Almost surely, 2^7890640 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 7890640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (9350964).

7890640 is an abundant number, since it is smaller than the sum of its proper divisors (10811288).

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

7890640 is a wasteful number, since it uses less digits than its factorization.

7890640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1927 (or 1921 counting only the distinct ones).

The product of its (nonzero) digits is 12096, while the sum is 34.

The square root of 7890640 is about 2809.0283017442. The cubic root of 7890640 is about 199.0844821971.

The spelling of 7890640 in words is "seven million, eight hundred ninety thousand, six hundred forty".