4021645 has 4 divisors (see below), whose sum is σ = 4825980. Its totient is φ = 3217312.

The previous prime is 4021627. The next prime is 4021651. The reversal of 4021645 is 5461204.

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 2518569 + 1503076 = 1587^2 + 1226^2 .

It is a cyclic number.

It is not a de Polignac number, because 4021645 - 2⁵ = 4021613 is a prime.

It is a super-3 number, since 3×4021645³ (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, 402160 + ... + 402169.

It is an arithmetic number, because the mean of its divisors is an integer number (1206495).

Almost surely, 2^4021645 is an apocalyptic number.

It is an amenable number.

4021645 is a deficient number, since it is larger than the sum of its proper divisors (804335).

4021645 is an equidigital number, since it uses as much as digits as its factorization.

4021645 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 804334.

The product of its (nonzero) digits is 960, while the sum is 22.

The square root of 4021645 is about 2005.4039493329. The cubic root of 4021645 is about 159.0259177454.

Adding to 4021645 its reverse (5461204), we get a palindrome (9482849).

The spelling of 4021645 in words is "four million, twenty-one thousand, six hundred forty-five".