4021009 has 2 divisors, whose sum is σ = 4021010. Its totient is φ = 4021008.

The previous prime is 4021001. The next prime is 4021013. The reversal of 4021009 is 9001204.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 2190400 + 1830609 = 1480^2 + 1353^2 .

It is a cyclic number.

It is not a de Polignac number, because 4021009 - 2³ = 4021001 is a prime.

It is an Ulam number.

4021009 is a lucky number.

It is a junction number, because it is equal to n+sod(n) for n = 4020983 and 4021001.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (4021001) by changing a digit.

It is a good prime.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2010504 + 2010505.

It is an arithmetic number, because the mean of its divisors is an integer number (2010505).

Almost surely, 2^4021009 is an apocalyptic number.

It is an amenable number.

4021009 is a deficient number, since it is larger than the sum of its proper divisors (1).

4021009 is an equidigital number, since it uses as much as digits as its factorization.

4021009 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 72, while the sum is 16.

The square root of 4021009 is about 2005.2453715194. The cubic root of 4021009 is about 159.0175342924.

The spelling of 4021009 in words is "four million, twenty-one thousand, nine".