4001521 has 2 divisors, whose sum is σ = 4001522. Its totient is φ = 4001520.

The previous prime is 4001509. The next prime is 4001527. The reversal of 4001521 is 1251004.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 4000000 + 1521 = 2000^2 + 39^2 .

It is a cyclic number.

It is not a de Polignac number, because 4001521 - 2⁹ = 4001009 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (4001527) 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 as a sum of consecutive naturals, namely, 2000760 + 2000761.

It is an arithmetic number, because the mean of its divisors is an integer number (2000761).

Almost surely, 2^4001521 is an apocalyptic number.

It is an amenable number.

4001521 is a deficient number, since it is larger than the sum of its proper divisors (1).

4001521 is an equidigital number, since it uses as much as digits as its factorization.

4001521 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 40, while the sum is 13.

The square root of 4001521 is about 2000.3802138594. The cubic root of 4001521 is about 158.7602229554.

Adding to 4001521 its reverse (1251004), we get a palindrome (5252525).

It can be divided in two parts, 400 and 1521, that multiplied together give a square (608400 = 780²).

The spelling of 4001521 in words is "four million, one thousand, five hundred twenty-one".