51221313 has 24 divisors (see below), whose sum is σ = 86923200. Its totient is φ = 28654560.

The previous prime is 51221297. The next prime is 51221327. The reversal of 51221313 is 31312215.

It is not a de Polignac number, because 51221313 - 2⁴ = 51221297 is a prime.

It is a super-3 number, since 3×51221313³ (a number of 24 digits) contains 333 as substring.

It is not an unprimeable number, because it can be changed into a prime (51221363) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 18613 + ... + 21186.

It is an arithmetic number, because the mean of its divisors is an integer number (3621800).

Almost surely, 2^51221313 is an apocalyptic number.

It is an amenable number.

51221313 is a deficient number, since it is larger than the sum of its proper divisors (35701887).

51221313 is a wasteful number, since it uses less digits than its factorization.

51221313 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 39829 (or 39826 counting only the distinct ones).

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

The square root of 51221313 is about 7156.9066641951. The cubic root of 51221313 is about 371.3786235949.

Adding to 51221313 its reverse (31312215), we get a palindrome (82533528).

The spelling of 51221313 in words is "fifty-one million, two hundred twenty-one thousand, three hundred thirteen".