2400021 has 24 divisors (see below), whose sum is σ = 3797976.
Its totient is φ = 1451520.
The previous prime is 2400019. The next prime is 2400031. The reversal of 2400021 is 1200042.
Adding to 2400021 its reverse (1200042), we get a palindrome (3600063).
2400021 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.
It can be written as a sum of positive squares in 4 ways, for example, as 239121 + 2160900 = 489^2 + 1470^2
It is not a de Polignac number, because 2400021 - 21 = 2400019 is a prime.
It is a Harshad number since it is a multiple of its sum of digits (9).
It is a Curzon number.
It is a junction number, because it is equal to n+sod(n) for n = 2399976 and 2400012.
It is a congruent number.
It is not an unprimeable number, because it can be changed into a prime (2400001) 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 23 ways as a sum of consecutive naturals, for example, 8401 + ... + 8681.
It is an arithmetic number, because the mean of its divisors is an integer number (158249).
22400021 is an apocalyptic number.
It is an amenable number.
2400021 is a deficient number, since it is larger than the sum of its proper divisors (1397955).
2400021 is a wasteful number, since it uses less digits than its factorization.
2400021 is an odious number, because the sum of its binary digits is odd.
The sum of its prime factors is 373 (or 370 counting only the distinct ones).
The product of its (nonzero) digits is 16, while the sum is 9.
The square root of 2400021 is about 1549.2001161890.
The cubic root of 2400021 is about 133.8869805178.
The spelling of 2400021 in words is "two million, four hundred thousand, twenty-one".