51511231 has 4 divisors (see below), whose sum is σ = 51527952. Its totient is φ = 51494512.

The previous prime is 51511217. The next prime is 51511247. The reversal of 51511231 is 13211515.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 51511231 - 2⁵ = 51511199 is a prime.

It is a super-2 number, since 2×51511231² = 5306813838270722, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 51511199 and 51511208.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51511531) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2251 + ... + 10396.

It is an arithmetic number, because the mean of its divisors is an integer number (12881988).

Almost surely, 2^51511231 is an apocalyptic number.

51511231 is a deficient number, since it is larger than the sum of its proper divisors (16721).

51511231 is a wasteful number, since it uses less digits than its factorization.

51511231 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16720.

The product of its digits is 150, while the sum is 19.

The square root of 51511231 is about 7177.1325053952. The cubic root of 51511231 is about 372.0779864053.

Adding to 51511231 its reverse (13211515), we get a palindrome (64722746).

The spelling of 51511231 in words is "fifty-one million, five hundred eleven thousand, two hundred thirty-one".