815666976401 has 2 divisors, whose sum is σ = 815666976402. Its totient is φ = 815666976400.

The previous prime is 815666976331. The next prime is 815666976433. The reversal of 815666976401 is 104679666518.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 724916016400 + 90750960001 = 851420^2 + 301249^2 .

It is a cyclic number.

It is not a de Polignac number, because 815666976401 - 2¹⁸ = 815666714257 is a prime.

It is a super-2 number, since 2×815666976401² (a number of 25 digits) contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (815666976491) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 407833488200 + 407833488201.

It is an arithmetic number, because the mean of its divisors is an integer number (407833488201).

Almost surely, 2^815666976401 is an apocalyptic number.

It is an amenable number.

815666976401 is a deficient number, since it is larger than the sum of its proper divisors (1).

815666976401 is an equidigital number, since it uses as much as digits as its factorization.

815666976401 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 13063680, while the sum is 59.

The spelling of 815666976401 in words is "eight hundred fifteen billion, six hundred sixty-six million, nine hundred seventy-six thousand, four hundred one".