2787840 has 180 divisors, whose sum is σ = 10612602. Its totient is φ = 675840.

The previous prime is 2787781. The next prime is 2787859. The reversal of 2787840 is 487872.

It can be written as a sum of positive squares in only one way, i.e., 2509056 + 278784 = 1584^2 + 528^2 .

It is a tau number, because it is divible by the number of its divisors (180).

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

It is an Ulam number.

It is a junction number, because it is equal to n+sod(n) for n = 2787795 and 2787804.

It is an unprimeable number.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 253435 + ... + 253445.

2^2787840 is an apocalyptic number.

2787840 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 2787840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (5306301).

2787840 is an abundant number, since it is smaller than the sum of its proper divisors (7824762).

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

2787840 is a wasteful number, since it uses less digits than its factorization.

2787840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 51 (or 21 counting only the distinct ones).

The product of its (nonzero) digits is 25088, while the sum is 36.

The square root of 2787840 is about 1669.6826045689. The cubic root of 2787840 is about 140.7416424825.

Subtracting from 2787840 its reverse (487872), we obtain a cube (2299968 = 132³).

It can be divided in two parts, 278 and 7840, that added together give a palindrome (8118).

The spelling of 2787840 in words is "two million, seven hundred eighty-seven thousand, eight hundred forty".