51313221 has 6 divisors (see below), whose sum is σ = 74119110. Its totient is φ = 34208808.

The previous prime is 51313219. The next prime is 51313231. The reversal of 51313221 is 12231315.

51313221 is a `hidden beast` number, since 513 + 132 + 21 = 666.

It can be written as a sum of positive squares in only one way, i.e., 49196196 + 2117025 = 7014^2 + 1455^2 .

It is not a de Polignac number, because 51313221 - 2¹ = 51313219 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 51313194 and 51313203.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51313201) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 2850726 + ... + 2850743.

It is an arithmetic number, because the mean of its divisors is an integer number (12353185).

Almost surely, 2^51313221 is an apocalyptic number.

It is an amenable number.

51313221 is a deficient number, since it is larger than the sum of its proper divisors (22805889).

51313221 is a wasteful number, since it uses less digits than its factorization.

51313221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5701475 (or 5701472 counting only the distinct ones).

The product of its digits is 180, while the sum is 18.

The square root of 51313221 is about 7163.3247169174. The cubic root of 51313221 is about 371.6006162887.

Adding to 51313221 its reverse (12231315), we get a palindrome (63544536).

The spelling of 51313221 in words is "fifty-one million, three hundred thirteen thousand, two hundred twenty-one".