2780640 has 72 divisors (see below), whose sum is σ = 9493848. Its totient is φ = 741120.

The previous prime is 2780623. The next prime is 2780641. The reversal of 2780640 is 460872.

2780640 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a tau number, because it is divible by the number of its divisors (72).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2780641) by changing a digit.

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 11 ways as a sum of consecutive naturals, for example, 475 + ... + 2405.

It is an arithmetic number, because the mean of its divisors is an integer number (131859).

2^2780640 is an apocalyptic number.

2780640 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 2780640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (4746924).

2780640 is an abundant number, since it is smaller than the sum of its proper divisors (6713208).

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

2780640 is a wasteful number, since it uses less digits than its factorization.

2780640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1952 (or 1941 counting only the distinct ones).

The product of its (nonzero) digits is 2688, while the sum is 27.

The square root of 2780640 is about 1667.5251122547. The cubic root of 2780640 is about 140.6203761443.

The spelling of 2780640 in words is "two million, seven hundred eighty thousand, six hundred forty".