813978961 has 2 divisors, whose sum is σ = 813978962. Its totient is φ = 813978960.

The previous prime is 813978953. The next prime is 813979037. The reversal of 813978961 is 169879318.

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., 526473025 + 287505936 = 22945^2 + 16956^2 .

It is a cyclic number.

It is not a de Polignac number, because 813978961 - 2³ = 813978953 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 813978899 and 813978908.

It is not a weakly prime, because it can be changed into another prime (813978911) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 406989480 + 406989481.

It is an arithmetic number, because the mean of its divisors is an integer number (406989481).

Almost surely, 2^813978961 is an apocalyptic number.

It is an amenable number.

813978961 is a deficient number, since it is larger than the sum of its proper divisors (1).

813978961 is an equidigital number, since it uses as much as digits as its factorization.

813978961 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 653184, while the sum is 52.

The square root of 813978961 is about 28530.3165247075. The cubic root of 813978961 is about 933.6936243216.

The spelling of 813978961 in words is "eight hundred thirteen million, nine hundred seventy-eight thousand, nine hundred sixty-one".