51521213 has 4 divisors (see below), whose sum is σ = 51782940. Its totient is φ = 51259488.

The previous prime is 51521209. The next prime is 51521263. The reversal of 51521213 is 31212515.

It is a happy number.

51521213 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 31212515 = 5 ⋅6242503.

It can be written as a sum of positive squares in 2 ways, for example, as 35736484 + 15784729 = 5978^2 + 3973^2 .

It is a cyclic number.

It is not a de Polignac number, because 51521213 - 2² = 51521209 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51521263) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 130568 + ... + 130961.

It is an arithmetic number, because the mean of its divisors is an integer number (12945735).

Almost surely, 2^51521213 is an apocalyptic number.

It is an amenable number.

51521213 is a deficient number, since it is larger than the sum of its proper divisors (261727).

51521213 is a wasteful number, since it uses less digits than its factorization.

51521213 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 261726.

The product of its digits is 300, while the sum is 20.

The square root of 51521213 is about 7177.8278747822. The cubic root of 51521213 is about 372.1020189804.

Adding to 51521213 its reverse (31212515), we get a palindrome (82733728).

The spelling of 51521213 in words is "fifty-one million, five hundred twenty-one thousand, two hundred thirteen".