813970921 has 2 divisors, whose sum is σ = 813970922. Its totient is φ = 813970920.

The previous prime is 813970879. The next prime is 813970933. The reversal of 813970921 is 129079318.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 516925696 + 297045225 = 22736^2 + 17235^2 .

It is a cyclic number.

It is not a de Polignac number, because 813970921 - 2⁷ = 813970793 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (813970021) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 406985460 + 406985461.

It is an arithmetic number, because the mean of its divisors is an integer number (406985461).

Almost surely, 2^813970921 is an apocalyptic number.

It is an amenable number.

813970921 is a deficient number, since it is larger than the sum of its proper divisors (1).

813970921 is an equidigital number, since it uses as much as digits as its factorization.

813970921 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 27216, while the sum is 40.

The square root of 813970921 is about 28530.1756216116. The cubic root of 813970921 is about 933.6905501547.

The spelling of 813970921 in words is "eight hundred thirteen million, nine hundred seventy thousand, nine hundred twenty-one".