51240043021 has 2 divisors, whose sum is σ = 51240043022. Its totient is φ = 51240043020.

The previous prime is 51240043013. The next prime is 51240043051. The reversal of 51240043021 is 12034004215.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 35934889225 + 15305153796 = 189565^2 + 123714^2 .

It is a cyclic number.

It is not a de Polignac number, because 51240043021 - 2³ = 51240043013 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 51240042983 and 51240043001.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (51240043051) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 25620021510 + 25620021511.

It is an arithmetic number, because the mean of its divisors is an integer number (25620021511).

Almost surely, 2^51240043021 is an apocalyptic number.

It is an amenable number.

51240043021 is a deficient number, since it is larger than the sum of its proper divisors (1).

51240043021 is an equidigital number, since it uses as much as digits as its factorization.

51240043021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 960, while the sum is 22.

Adding to 51240043021 its reverse (12034004215), we get a palindrome (63274047236).

The spelling of 51240043021 in words is "fifty-one billion, two hundred forty million, forty-three thousand, twenty-one".