2809840 has 80 divisors (see below), whose sum is σ = 7428096. Its totient is φ = 979200.

The previous prime is 2809837. The next prime is 2809847. The reversal of 2809840 is 489082.

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

It is a Harshad number since it is a multiple of its sum of digits (31).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2809847) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 27229 + ... + 27331.

2^2809840 is an apocalyptic number.

2809840 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 2809840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3714048).

2809840 is an abundant number, since it is smaller than the sum of its proper divisors (4618256).

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

2809840 is a wasteful number, since it uses less digits than its factorization.

2809840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 158 (or 152 counting only the distinct ones).

The product of its (nonzero) digits is 4608, while the sum is 31.

The square root of 2809840 is about 1676.2577367458. The cubic root of 2809840 is about 141.1108897474.

The spelling of 2809840 in words is "two million, eight hundred nine thousand, eight hundred forty".