811623221 has 2 divisors, whose sum is σ = 811623222. Its totient is φ = 811623220.

The previous prime is 811623217. The next prime is 811623229. The reversal of 811623221 is 122326118.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 811623121 + 100 = 28489^2 + 10^2 .

It is a cyclic number.

It is not a de Polignac number, because 811623221 - 2² = 811623217 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (811623229) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 405811610 + 405811611.

It is an arithmetic number, because the mean of its divisors is an integer number (405811611).

Almost surely, 2^811623221 is an apocalyptic number.

It is an amenable number.

811623221 is a deficient number, since it is larger than the sum of its proper divisors (1).

811623221 is an equidigital number, since it uses as much as digits as its factorization.

811623221 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1152, while the sum is 26.

The square root of 811623221 is about 28489.0017550633. The cubic root of 811623221 is about 932.7920184075.

Adding to 811623221 its reverse (122326118), we get a palindrome (933949339).

The spelling of 811623221 in words is "eight hundred eleven million, six hundred twenty-three thousand, two hundred twenty-one".