51251615209 has 2 divisors, whose sum is σ = 51251615210. Its totient is φ = 51251615208.

The previous prime is 51251615201. The next prime is 51251615269. The reversal of 51251615209 is 90251615215.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 50354013609 + 897601600 = 224397^2 + 29960^2 .

It is a cyclic number.

It is not a de Polignac number, because 51251615209 - 2³ = 51251615201 is a prime.

It is a super-2 number, since 2×51251615209² (a number of 22 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (51251615201) 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, 25625807604 + 25625807605.

It is an arithmetic number, because the mean of its divisors is an integer number (25625807605).

Almost surely, 2^51251615209 is an apocalyptic number.

It is an amenable number.

51251615209 is a deficient number, since it is larger than the sum of its proper divisors (1).

51251615209 is an equidigital number, since it uses as much as digits as its factorization.

51251615209 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 27000, while the sum is 37.

It can be divided in two parts, 512516 and 15209, that added together give a palindrome (527725).

The spelling of 51251615209 in words is "fifty-one billion, two hundred fifty-one million, six hundred fifteen thousand, two hundred nine".