21220123 has 4 divisors (see below), whose sum is σ = 21230560. Its totient is φ = 21209688.

The previous prime is 21220109. The next prime is 21220153. The reversal of 21220123 is 32102212.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 21220123 - 2¹⁷ = 21089051 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21220103) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1068 + ... + 6601.

It is an arithmetic number, because the mean of its divisors is an integer number (5307640).

Almost surely, 2^21220123 is an apocalyptic number.

21220123 is a deficient number, since it is larger than the sum of its proper divisors (10437).

21220123 is an equidigital number, since it uses as much as digits as its factorization.

21220123 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10436.

The product of its (nonzero) digits is 48, while the sum is 13.

The square root of 21220123 is about 4606.5304731435. The cubic root of 21220123 is about 276.8530414673.

Adding to 21220123 its reverse (32102212), we get a palindrome (53322335).

The spelling of 21220123 in words is "twenty-one million, two hundred twenty thousand, one hundred twenty-three".