4001645 has 4 divisors (see below), whose sum is σ = 4801980. Its totient is φ = 3201312.

The previous prime is 4001639. The next prime is 4001689. The reversal of 4001645 is 5461004.

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 1990921 + 2010724 = 1411^2 + 1418^2 .

It is a cyclic number.

It is not a de Polignac number, because 4001645 - 2⁴ = 4001629 is a prime.

It is a super-3 number, since 3×4001645³ (a number of 21 digits) contains 333 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 400160 + ... + 400169.

It is an arithmetic number, because the mean of its divisors is an integer number (1200495).

Almost surely, 2^4001645 is an apocalyptic number.

It is an amenable number.

4001645 is a deficient number, since it is larger than the sum of its proper divisors (800335).

4001645 is an equidigital number, since it uses as much as digits as its factorization.

4001645 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 800334.

The product of its (nonzero) digits is 480, while the sum is 20.

The square root of 4001645 is about 2000.4112077271. The cubic root of 4001645 is about 158.7618628372.

Adding to 4001645 its reverse (5461004), we get a palindrome (9462649).

The spelling of 4001645 in words is "four million, one thousand, six hundred forty-five".