6539221 has 4 divisors (see below), whose sum is σ = 7042252. Its totient is φ = 6036192.

The previous prime is 6539209. The next prime is 6539243. The reversal of 6539221 is 1229356.

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 264196 + 6275025 = 514^2 + 2505^2 .

It is a cyclic number.

It is not a de Polignac number, because 6539221 - 2¹¹ = 6537173 is a prime.

It is a super-2 number, since 2×6539221² = 85522822573682, which contains 22 as substring.

It is a Duffinian number.

6539221 is a lucky number.

It is a self number, because there is not a number n which added to its sum of digits gives 6539221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6539201) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 251496 + ... + 251521.

It is an arithmetic number, because the mean of its divisors is an integer number (1760563).

Almost surely, 2^6539221 is an apocalyptic number.

It is an amenable number.

6539221 is a deficient number, since it is larger than the sum of its proper divisors (503031).

6539221 is a wasteful number, since it uses less digits than its factorization.

6539221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 503030.

The product of its digits is 3240, while the sum is 28.

The square root of 6539221 is about 2557.1900594207. The cubic root of 6539221 is about 187.0001715804. Note that the first 3 decimals are identical.

The spelling of 6539221 in words is "six million, five hundred thirty-nine thousand, two hundred twenty-one".