2781220 has 48 divisors (see below), whose sum is σ = 6632640. Its totient is φ = 971136.

The previous prime is 2781211. The next prime is 2781221. The reversal of 2781220 is 221872.

2781220 = 174² + 175² + ... + 238².

It is a junction number, because it is equal to n+sod(n) for n = 2781191 and 2781200.

It is not an unprimeable number, because it can be changed into a prime (2781221) 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, 4659 + ... + 5221.

It is an arithmetic number, because the mean of its divisors is an integer number (138180).

2^2781220 is an apocalyptic number.

2781220 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 2781220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3316320).

2781220 is an abundant number, since it is smaller than the sum of its proper divisors (3851420).

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

2781220 is a wasteful number, since it uses less digits than its factorization.

2781220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 604 (or 602 counting only the distinct ones).

The product of its (nonzero) digits is 448, while the sum is 22.

The square root of 2781220 is about 1667.6990136113. The cubic root of 2781220 is about 140.6301525684.

The spelling of 2781220 in words is "two million, seven hundred eighty-one thousand, two hundred twenty".