812921 has 2 divisors, whose sum is σ = 812922. Its totient is φ = 812920.

The previous prime is 812869. The next prime is 812939. The reversal of 812921 is 129218.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 525625 + 287296 = 725^2 + 536^2 .

It is a cyclic number.

It is not a de Polignac number, because 812921 - 2⁶ = 812857 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is an alternating number because its digits alternate between even and odd.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (812221) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 406460 + 406461.

It is an arithmetic number, because the mean of its divisors is an integer number (406461).

2⁸¹²⁹²¹ is an apocalyptic number.

It is an amenable number.

812921 is a deficient number, since it is larger than the sum of its proper divisors (1).

812921 is an equidigital number, since it uses as much as digits as its factorization.

812921 is an evil number, because the sum of its binary digits is even.

The product of its digits is 288, while the sum is 23.

The square root of 812921 is about 901.6213174055. The cubic root of 812921 is about 93.3288929293.

The spelling of 812921 in words is "eight hundred twelve thousand, nine hundred twenty-one".