4039921 has 4 divisors (see below), whose sum is σ = 4047732. Its totient is φ = 4032112.

The previous prime is 4039901. The next prime is 4039949. The reversal of 4039921 is 1299304.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 1527696 + 2512225 = 1236^2 + 1585^2 .

It is a cyclic number.

It is not a de Polignac number, because 4039921 - 2⁷ = 4039793 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 4039921.

It is not an unprimeable number, because it can be changed into a prime (4039901) 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 3 ways as a sum of consecutive naturals, for example, 3070 + ... + 4183.

It is an arithmetic number, because the mean of its divisors is an integer number (1011933).

Almost surely, 2^4039921 is an apocalyptic number.

It is an amenable number.

4039921 is a deficient number, since it is larger than the sum of its proper divisors (7811).

4039921 is an equidigital number, since it uses as much as digits as its factorization.

4039921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7810.

The product of its (nonzero) digits is 1944, while the sum is 28.

The square root of 4039921 is about 2009.9554721436. The cubic root of 4039921 is about 159.2664466994.

The spelling of 4039921 in words is "four million, thirty-nine thousand, nine hundred twenty-one".