15818509121 has 2 divisors, whose sum is σ = 15818509122. Its totient is φ = 15818509120.

The previous prime is 15818509079. The next prime is 15818509151. The reversal of 15818509121 is 12190581851.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 10513426225 + 5305082896 = 102535^2 + 72836^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-15818509121 is a prime.

It is a super-2 number, since 2×15818509121² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (15818509151) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 7909254560 + 7909254561.

It is an arithmetic number, because the mean of its divisors is an integer number (7909254561).

Almost surely, 2^15818509121 is an apocalyptic number.

It is an amenable number.

15818509121 is a deficient number, since it is larger than the sum of its proper divisors (1).

15818509121 is an equidigital number, since it uses as much as digits as its factorization.

15818509121 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 28800, while the sum is 41.

The spelling of 15818509121 in words is "fifteen billion, eight hundred eighteen million, five hundred nine thousand, one hundred twenty-one".