51331021 has 4 divisors (see below), whose sum is σ = 58664032. Its totient is φ = 43998012.

The previous prime is 51331019. The next prime is 51331051. The reversal of 51331021 is 12013315.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 12013315 = 5 ⋅2402663.

It is a cyclic number.

It is not a de Polignac number, because 51331021 - 2¹ = 51331019 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 51330986 and 51331004.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51331051) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3666495 + ... + 3666508.

It is an arithmetic number, because the mean of its divisors is an integer number (14666008).

Almost surely, 2^51331021 is an apocalyptic number.

It is an amenable number.

51331021 is a deficient number, since it is larger than the sum of its proper divisors (7333011).

51331021 is an equidigital number, since it uses as much as digits as its factorization.

51331021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7333010.

The product of its (nonzero) digits is 90, while the sum is 16.

The square root of 51331021 is about 7164.5670490268. The cubic root of 51331021 is about 371.6435793962.

Adding to 51331021 its reverse (12013315), we get a palindrome (63344336).

The spelling of 51331021 in words is "fifty-one million, three hundred thirty-one thousand, twenty-one".