51240221 has 2 divisors, whose sum is σ = 51240222. Its totient is φ = 51240220.

The previous prime is 51240121. The next prime is 51240253. The reversal of 51240221 is 12204215.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 29008996 + 22231225 = 5386^2 + 4715^2 .

It is a cyclic number.

It is not a de Polignac number, because 51240221 - 2¹⁸ = 50978077 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 51240221.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (51240121) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 25620110 + 25620111.

It is an arithmetic number, because the mean of its divisors is an integer number (25620111).

Almost surely, 2^51240221 is an apocalyptic number.

It is an amenable number.

51240221 is a deficient number, since it is larger than the sum of its proper divisors (1).

51240221 is an equidigital number, since it uses as much as digits as its factorization.

51240221 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 160, while the sum is 17.

The square root of 51240221 is about 7158.2275040683. The cubic root of 51240221 is about 371.4243152724.

Adding to 51240221 its reverse (12204215), we get a palindrome (63444436).

The spelling of 51240221 in words is "fifty-one million, two hundred forty thousand, two hundred twenty-one".