2809040 has 80 divisors (see below), whose sum is σ = 7322448. Its totient is φ = 995328.

The previous prime is 2809019. The next prime is 2809069. The reversal of 2809040 is 409082.

2809040 is digitally balanced in base 2 and base 5, because in such bases it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 8 ways, for example, as 64 + 2808976 = 8^2 + 1676^2 .

It is a tau number, because it is divible by the number of its divisors (80).

It is a junction number, because it is equal to n+sod(n) for n = 2808997 and 2809015.

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 15 ways as a sum of consecutive naturals, for example, 38444 + ... + 38516.

2^2809040 is an apocalyptic number.

2809040 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 2809040, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3661224).

2809040 is an abundant number, since it is smaller than the sum of its proper divisors (4513408).

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

2809040 is a wasteful number, since it uses less digits than its factorization.

2809040 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 136 (or 130 counting only the distinct ones).

The product of its (nonzero) digits is 576, while the sum is 23.

The square root of 2809040 is about 1676.0190929700. The cubic root of 2809040 is about 141.0974964074.

It can be divided in two parts, 28090 and 40, that multiplied together give a square (1123600 = 1060²).

The spelling of 2809040 in words is "two million, eight hundred nine thousand, forty".