51521231 has 4 divisors (see below), whose sum is σ = 51537192. Its totient is φ = 51505272.

The previous prime is 51521209. The next prime is 51521263. The reversal of 51521231 is 13212515.

It is a happy number.

51521231 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.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-51521231 is a prime.

It is a super-2 number, since 2×51521231² = 5308874487510722, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51521201) 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, 1241 + ... + 10226.

It is an arithmetic number, because the mean of its divisors is an integer number (12884298).

Almost surely, 2^51521231 is an apocalyptic number.

51521231 is a deficient number, since it is larger than the sum of its proper divisors (15961).

51521231 is a wasteful number, since it uses less digits than its factorization.

51521231 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15960.

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

The square root of 51521231 is about 7177.8291286433. The cubic root of 51521231 is about 372.1020623142.

Adding to 51521231 its reverse (13212515), we get a palindrome (64733746).

The spelling of 51521231 in words is "fifty-one million, five hundred twenty-one thousand, two hundred thirty-one".