251216313221509 has 2 divisors, whose sum is σ = 251216313221510. Its totient is φ = 251216313221508.

The previous prime is 251216313221507. The next prime is 251216313221539. The reversal of 251216313221509 is 905122313612152.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 178449442099009 + 72766871122500 = 13358497^2 + 8530350^2 .

It is a cyclic number.

It is not a de Polignac number, because 251216313221509 - 2¹ = 251216313221507 is a prime.

Together with 251216313221507, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (251216313221507) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 125608156610754 + 125608156610755.

It is an arithmetic number, because the mean of its divisors is an integer number (125608156610755).

Almost surely, 2^{251216313221509} is an apocalyptic number.

It is an amenable number.

251216313221509 is a deficient number, since it is larger than the sum of its proper divisors (1).

251216313221509 is an equidigital number, since it uses as much as digits as its factorization.

251216313221509 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 194400, while the sum is 43.

The spelling of 251216313221509 in words is "two hundred fifty-one trillion, two hundred sixteen billion, three hundred thirteen million, two hundred twenty-one thousand, five hundred nine".