2781921 has 8 divisors (see below), whose sum is σ = 3732640. Its totient is φ = 1842912.

The previous prime is 2781913. The next prime is 2781929. The reversal of 2781921 is 1291872.

2781921 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an interprime number because it is at equal distance from previous prime (2781913) and next prime (2781929).

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 2781921 - 2³ = 2781913 is a prime.

It is a Duffinian number.

It is a Curzon number.

2781921 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (2781929) 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 7 ways as a sum of consecutive naturals, for example, 2356 + ... + 3333.

It is an arithmetic number, because the mean of its divisors is an integer number (466580).

2^2781921 is an apocalyptic number.

It is an amenable number.

2781921 is a deficient number, since it is larger than the sum of its proper divisors (950719).

2781921 is a wasteful number, since it uses less digits than its factorization.

2781921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5855.

The product of its digits is 2016, while the sum is 30.

The square root of 2781921 is about 1667.9091701888. The cubic root of 2781921 is about 140.6419667430.

The spelling of 2781921 in words is "two million, seven hundred eighty-one thousand, nine hundred twenty-one".