3640021 has 16 divisors (see below), whose sum is σ = 4652928. Its totient is φ = 2764800.

The previous prime is 3640019. The next prime is 3640027. The reversal of 3640021 is 1200463.

It is a 6-Lehmer number, since φ(3640021) divides (3640021-1)⁶.

It is a cyclic number.

It is not a de Polignac number, because 3640021 - 2¹ = 3640019 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 3639977 and 3640004.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (3640027) 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 15 ways as a sum of consecutive naturals, for example, 2581 + ... + 3733.

It is an arithmetic number, because the mean of its divisors is an integer number (290808).

Almost surely, 2^3640021 is an apocalyptic number.

It is an amenable number.

3640021 is a deficient number, since it is larger than the sum of its proper divisors (1012907).

3640021 is a wasteful number, since it uses less digits than its factorization.

3640021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1212.

The product of its (nonzero) digits is 144, while the sum is 16.

The square root of 3640021 is about 1907.8839063213. The cubic root of 3640021 is about 153.8277294410.

Adding to 3640021 its reverse (1200463), we get a palindrome (4840484).

The spelling of 3640021 in words is "three million, six hundred forty thousand, twenty-one".