811205123 has 2 divisors, whose sum is σ = 811205124. Its totient is φ = 811205122.

The previous prime is 811205051. The next prime is 811205173. The reversal of 811205123 is 321502118.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-811205123 is a prime.

It is not a weakly prime, because it can be changed into another prime (811205173) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 405602561 + 405602562.

It is an arithmetic number, because the mean of its divisors is an integer number (405602562).

Almost surely, 2^811205123 is an apocalyptic number.

811205123 is a deficient number, since it is larger than the sum of its proper divisors (1).

811205123 is an equidigital number, since it uses as much as digits as its factorization.

811205123 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 480, while the sum is 23.

The square root of 811205123 is about 28481.6629254684. The cubic root of 811205123 is about 932.6318186768.

The spelling of 811205123 in words is "eight hundred eleven million, two hundred five thousand, one hundred twenty-three".