6556351221 has 16 divisors (see below), whose sum is σ = 11100700800. Its totient is φ = 3746486304.

The previous prime is 6556351213. The next prime is 6556351259. The reversal of 6556351221 is 1221536556.

6556351221 is a `hidden beast` number, since 6 + 5 + 5 + 635 + 12 + 2 + 1 = 666.

It is not a de Polignac number, because 6556351221 - 2³ = 6556351213 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6556351721) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 17344656 + ... + 17345033.

It is an arithmetic number, because the mean of its divisors is an integer number (693793800).

Almost surely, 2^6556351221 is an apocalyptic number.

It is an amenable number.

6556351221 is a deficient number, since it is larger than the sum of its proper divisors (4544349579).

6556351221 is a wasteful number, since it uses less digits than its factorization.

6556351221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 34689705 (or 34689699 counting only the distinct ones).

The product of its digits is 54000, while the sum is 36.

The square root of 6556351221 is about 80971.2987483837. The cubic root of 6556351221 is about 1871.6331849286.

Adding to 6556351221 its reverse (1221536556), we get a palindrome (7777887777).

The spelling of 6556351221 in words is "six billion, five hundred fifty-six million, three hundred fifty-one thousand, two hundred twenty-one".