2721921 has 24 divisors (see below), whose sum is σ = 4122720. Its totient is φ = 1587456.

The previous prime is 2721913. The next prime is 2721947. The reversal of 2721921 is 1291272.

It is not a de Polignac number, because 2721921 - 2³ = 2721913 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 2721891 and 2721900.

It is not an unprimeable number, because it can be changed into a prime (2721421) 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 23 ways as a sum of consecutive naturals, for example, 51331 + ... + 51383.

It is an arithmetic number, because the mean of its divisors is an integer number (171780).

2^2721921 is an apocalyptic number.

It is an amenable number.

2721921 is a deficient number, since it is larger than the sum of its proper divisors (1400799).

2721921 is a wasteful number, since it uses less digits than its factorization.

2721921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 145 (or 92 counting only the distinct ones).

The product of its digits is 504, while the sum is 24.

The square root of 2721921 is about 1649.8245361250. The cubic root of 2721921 is about 139.6234951683.

The spelling of 2721921 in words is "two million, seven hundred twenty-one thousand, nine hundred twenty-one".