51538021 has 2 divisors, whose sum is σ = 51538022. Its totient is φ = 51538020.

The previous prime is 51538001. The next prime is 51538043. The reversal of 51538021 is 12083515.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 32615521 + 18922500 = 5711^2 + 4350^2 .

It is a cyclic number.

It is not a de Polignac number, because 51538021 - 2²³ = 43149413 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (51538001) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 25769010 + 25769011.

It is an arithmetic number, because the mean of its divisors is an integer number (25769011).

Almost surely, 2^51538021 is an apocalyptic number.

It is an amenable number.

51538021 is a deficient number, since it is larger than the sum of its proper divisors (1).

51538021 is an equidigital number, since it uses as much as digits as its factorization.

51538021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1200, while the sum is 25.

The square root of 51538021 is about 7178.9986070482. The cubic root of 51538021 is about 372.1424787598.

The spelling of 51538021 in words is "fifty-one million, five hundred thirty-eight thousand, twenty-one".