815837688121 has 2 divisors, whose sum is σ = 815837688122. Its totient is φ = 815837688120.

The previous prime is 815837688109. The next prime is 815837688209. The reversal of 815837688121 is 121886738518.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 661554489600 + 154283198521 = 813360^2 + 392789^2 .

It is a cyclic number.

It is not a de Polignac number, because 815837688121 - 2⁵ = 815837688089 is a prime.

It is a super-2 number, since 2×815837688121² (a number of 25 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (815837688221) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 407918844060 + 407918844061.

It is an arithmetic number, because the mean of its divisors is an integer number (407918844061).

Almost surely, 2^815837688121 is an apocalyptic number.

It is an amenable number.

815837688121 is a deficient number, since it is larger than the sum of its proper divisors (1).

815837688121 is an equidigital number, since it uses as much as digits as its factorization.

815837688121 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 5160960, while the sum is 58.

The spelling of 815837688121 in words is "eight hundred fifteen billion, eight hundred thirty-seven million, six hundred eighty-eight thousand, one hundred twenty-one".