251261602121 has 2 divisors, whose sum is σ = 251261602122. Its totient is φ = 251261602120.

The previous prime is 251261602099. The next prime is 251261602129. The reversal of 251261602121 is 121206162152.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 190148323600 + 61113278521 = 436060^2 + 247211^2 .

It is a cyclic number.

It is not a de Polignac number, because 251261602121 - 2¹⁸ = 251261339977 is a prime.

It is not a weakly prime, because it can be changed into another prime (251261602129) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 125630801060 + 125630801061.

It is an arithmetic number, because the mean of its divisors is an integer number (125630801061).

Almost surely, 2^251261602121 is an apocalyptic number.

It is an amenable number.

251261602121 is a deficient number, since it is larger than the sum of its proper divisors (1).

251261602121 is an equidigital number, since it uses as much as digits as its factorization.

251261602121 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2880, while the sum is 29.

Adding to 251261602121 its reverse (121206162152), we get a palindrome (372467764273).

The spelling of 251261602121 in words is "two hundred fifty-one billion, two hundred sixty-one million, six hundred two thousand, one hundred twenty-one".