51645221 has 2 divisors, whose sum is σ = 51645222. Its totient is φ = 51645220.

The previous prime is 51645203. The next prime is 51645227. The reversal of 51645221 is 12254615.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 26894596 + 24750625 = 5186^2 + 4975^2 .

It is a cyclic number.

It is not a de Polignac number, because 51645221 - 2⁶ = 51645157 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (51645227) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 25822610 + 25822611.

It is an arithmetic number, because the mean of its divisors is an integer number (25822611).

Almost surely, 2^51645221 is an apocalyptic number.

It is an amenable number.

51645221 is a deficient number, since it is larger than the sum of its proper divisors (1).

51645221 is an equidigital number, since it uses as much as digits as its factorization.

51645221 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2400, while the sum is 26.

The square root of 51645221 is about 7186.4609509828. The cubic root of 51645221 is about 372.4003210609.

Adding to 51645221 its reverse (12254615), we get a palindrome (63899836).

The spelling of 51645221 in words is "fifty-one million, six hundred forty-five thousand, two hundred twenty-one".