4191021 has 14 divisors (see below), whose sum is σ = 6284750. Its totient is φ = 2793528.

The previous prime is 4191017. The next prime is 4191041. The reversal of 4191021 is 1201914.

It can be written as a sum of positive squares in only one way, i.e., 2368521 + 1822500 = 1539^2 + 1350^2 .

It is not a de Polignac number, because 4191021 - 2² = 4191017 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 4190985 and 4191003.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (4191041) by changing a digit.

It is a polite number, since it can be written in 13 ways as a sum of consecutive naturals, for example, 2146 + ... + 3603.

Almost surely, 2^4191021 is an apocalyptic number.

It is an amenable number.

4191021 is a deficient number, since it is larger than the sum of its proper divisors (2093729).

4191021 is an frugal number, since it uses more digits than its factorization.

4191021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5767 (or 5752 counting only the distinct ones).

The product of its (nonzero) digits is 72, while the sum is 18.

The square root of 4191021 is about 2047.1983294249. The cubic root of 4191021 is about 161.2278065724.

Adding to 4191021 its reverse (1201914), we get a palindrome (5392935).

The spelling of 4191021 in words is "four million, one hundred ninety-one thousand, twenty-one".