820705123 has 4 divisors (see below), whose sum is σ = 937948720. Its totient is φ = 703461528.

The previous prime is 820705063. The next prime is 820705147. The reversal of 820705123 is 321507028.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 820705123 - 2²⁹ = 283834211 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 820705091 and 820705100.

It is not an unprimeable number, because it can be changed into a prime (820706123) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 58621788 + ... + 58621801.

It is an arithmetic number, because the mean of its divisors is an integer number (234487180).

Almost surely, 2^820705123 is an apocalyptic number.

820705123 is a deficient number, since it is larger than the sum of its proper divisors (117243597).

820705123 is a wasteful number, since it uses less digits than its factorization.

820705123 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 117243596.

The product of its (nonzero) digits is 3360, while the sum is 28.

The square root of 820705123 is about 28647.9514625392. The cubic root of 820705123 is about 936.2583733326.

The spelling of 820705123 in words is "eight hundred twenty million, seven hundred five thousand, one hundred twenty-three".