6615221 has 2 divisors, whose sum is σ = 6615222. Its totient is φ = 6615220.

The previous prime is 6615199. The next prime is 6615229. The reversal of 6615221 is 1225166.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 4468996 + 2146225 = 2114^2 + 1465^2 .

It is a cyclic number.

It is not a de Polignac number, because 6615221 - 2⁶ = 6615157 is a prime.

It is a super-2 number, since 2×6615221² = 87522297757682, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (6615229) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3307610 + 3307611.

It is an arithmetic number, because the mean of its divisors is an integer number (3307611).

Almost surely, 2^6615221 is an apocalyptic number.

It is an amenable number.

6615221 is a deficient number, since it is larger than the sum of its proper divisors (1).

6615221 is an equidigital number, since it uses as much as digits as its factorization.

6615221 is an evil number, because the sum of its binary digits is even.

The product of its digits is 720, while the sum is 23.

The square root of 6615221 is about 2572.0071928360. The cubic root of 6615221 is about 187.7218328516.

The spelling of 6615221 in words is "six million, six hundred fifteen thousand, two hundred twenty-one".