51306221 has 4 divisors (see below), whose sum is σ = 54324252. Its totient is φ = 48288192.

The previous prime is 51306197. The next prime is 51306239. The reversal of 51306221 is 12260315.

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 44488900 + 6817321 = 6670^2 + 2611^2 .

It is a cyclic number.

It is not a de Polignac number, because 51306221 - 2¹⁰ = 51305197 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 51306193 and 51306202.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51306421) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1508990 + ... + 1509023.

It is an arithmetic number, because the mean of its divisors is an integer number (13581063).

Almost surely, 2^51306221 is an apocalyptic number.

It is an amenable number.

51306221 is a deficient number, since it is larger than the sum of its proper divisors (3018031).

51306221 is a wasteful number, since it uses less digits than its factorization.

51306221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3018030.

The product of its (nonzero) digits is 360, while the sum is 20.

The square root of 51306221 is about 7162.8361003167. The cubic root of 51306221 is about 371.5837179628.

Adding to 51306221 its reverse (12260315), we get a palindrome (63566536).

The spelling of 51306221 in words is "fifty-one million, three hundred six thousand, two hundred twenty-one".