2781216 has 120 divisors (see below), whose sum is σ = 8690220. Its totient is φ = 870912.

The previous prime is 2781211. The next prime is 2781221. The reversal of 2781216 is 6121872.

It is an interprime number because it is at equal distance from previous prime (2781211) and next prime (2781221).

It can be written as a sum of positive squares in 2 ways, for example, as 2624400 + 156816 = 1620^2 + 396^2 .

It is a Harshad number since it is a multiple of its sum of digits (27).

It is an alternating number because its digits alternate between even and odd.

It is a self number, because there is not a number n which added to its sum of digits gives 2781216.

It is not an unprimeable number, because it can be changed into a prime (2781211) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 75150 + ... + 75186.

2^2781216 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 2781216, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (4345110).

2781216 is an abundant number, since it is smaller than the sum of its proper divisors (5909004).

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

2781216 is a wasteful number, since it uses less digits than its factorization.

2781216 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 88 (or 71 counting only the distinct ones).

The product of its digits is 1344, while the sum is 27.

The square root of 2781216 is about 1667.6978143537. The cubic root of 2781216 is about 140.6300851494.

The spelling of 2781216 in words is "two million, seven hundred eighty-one thousand, two hundred sixteen".