21202123 has 4 divisors (see below), whose sum is σ = 21653280. Its totient is φ = 20750968.

The previous prime is 21202121. The next prime is 21202127. The reversal of 21202123 is 32120212.

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 21202123 - 2¹ = 21202121 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21202121) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 225508 + ... + 225601.

It is an arithmetic number, because the mean of its divisors is an integer number (5413320).

Almost surely, 2^21202123 is an apocalyptic number.

21202123 is a deficient number, since it is larger than the sum of its proper divisors (451157).

21202123 is an equidigital number, since it uses as much as digits as its factorization.

21202123 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 451156.

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

The square root of 21202123 is about 4604.5763105849. The cubic root of 21202123 is about 276.7747389922.

Adding to 21202123 its reverse (32120212), we get a palindrome (53322335).

It can be divided in two parts, 2120212 and 3, that multiplied together give a palindrome (6360636).

The spelling of 21202123 in words is "twenty-one million, two hundred two thousand, one hundred twenty-three".