2781945 has 20 divisors (see below), whose sum is σ = 4987620. Its totient is φ = 1483488.

The previous prime is 2781937. The next prime is 2781949. The reversal of 2781945 is 5491872.

It can be written as a sum of positive squares in 2 ways, for example, as 385641 + 2396304 = 621^2 + 1548^2 .

It is not a de Polignac number, because 2781945 - 2³ = 2781937 is a prime.

2781945 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (2781949) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 3030 + ... + 3839.

It is an arithmetic number, because the mean of its divisors is an integer number (249381).

2^2781945 is an apocalyptic number.

It is an amenable number.

2781945 is a deficient number, since it is larger than the sum of its proper divisors (2205675).

2781945 is an equidigital number, since it uses as much as digits as its factorization.

2781945 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6886 (or 6877 counting only the distinct ones).

The product of its digits is 20160, while the sum is 36.

The square root of 2781945 is about 1667.9163648097. The cubic root of 2781945 is about 140.6423711874.

The spelling of 2781945 in words is "two million, seven hundred eighty-one thousand, nine hundred forty-five".