51515301221 has 2 divisors, whose sum is σ = 51515301222. Its totient is φ = 51515301220.

The previous prime is 51515301209. The next prime is 51515301239. The reversal of 51515301221 is 12210351515.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 27640725025 + 23874576196 = 166255^2 + 154514^2 .

It is a cyclic number.

It is not a de Polignac number, because 51515301221 - 2²⁶ = 51448192357 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (51515301281) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 25757650610 + 25757650611.

It is an arithmetic number, because the mean of its divisors is an integer number (25757650611).

Almost surely, 2^51515301221 is an apocalyptic number.

It is an amenable number.

51515301221 is a deficient number, since it is larger than the sum of its proper divisors (1).

51515301221 is an equidigital number, since it uses as much as digits as its factorization.

51515301221 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1500, while the sum is 26.

Adding to 51515301221 its reverse (12210351515), we get a palindrome (63725652736).

The spelling of 51515301221 in words is "fifty-one billion, five hundred fifteen million, three hundred one thousand, two hundred twenty-one".