2540021 has 16 divisors (see below), whose sum is σ = 3006720. Its totient is φ = 2127040.

The previous prime is 2540011. The next prime is 2540033. The reversal of 2540021 is 1200452.

It is a de Polignac number, because none of the positive numbers 2^k-2540021 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 2539978 and 2540005.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2540011) 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, 54020 + ... + 54066.

It is an arithmetic number, because the mean of its divisors is an integer number (187920).

2^2540021 is an apocalyptic number.

It is an amenable number.

2540021 is a deficient number, since it is larger than the sum of its proper divisors (466699).

2540021 is an equidigital number, since it uses as much as digits as its factorization.

2540021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 109 (or 75 counting only the distinct ones).

The product of its (nonzero) digits is 80, while the sum is 14.

The square root of 2540021 is about 1593.7443333233. The cubic root of 2540021 is about 136.4412749934.

Adding to 2540021 its reverse (1200452), we get a palindrome (3740473).

The spelling of 2540021 in words is "two million, five hundred forty thousand, twenty-one".