821621123 has 4 divisors (see below), whose sum is σ = 864864360. Its totient is φ = 778377888.

The previous prime is 821621107. The next prime is 821621153. The reversal of 821621123 is 321126128.

821621123 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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

It is a cyclic number.

It is not a de Polignac number, because 821621123 - 2⁴ = 821621107 is a prime.

It is a super-2 number, since 2×821621123² = 1350122539519562258, which contains 22 as substring.

It is a Duffinian number.

It is a zygodrome in base 2.

It is a junction number, because it is equal to n+sod(n) for n = 821621092 and 821621101.

It is not an unprimeable number, because it can be changed into a prime (821621153) 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, 21621590 + ... + 21621627.

It is an arithmetic number, because the mean of its divisors is an integer number (216216090).

Almost surely, 2^821621123 is an apocalyptic number.

821621123 is a deficient number, since it is larger than the sum of its proper divisors (43243237).

821621123 is a wasteful number, since it uses less digits than its factorization.

821621123 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 43243236.

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

The square root of 821621123 is about 28663.9341856627. The cubic root of 821621123 is about 936.6065673345.

The spelling of 821621123 in words is "eight hundred twenty-one million, six hundred twenty-one thousand, one hundred twenty-three".