21122423 has 4 divisors (see below), whose sum is σ = 24139920. Its totient is φ = 18104928.

The previous prime is 21122419. The next prime is 21122443. The reversal of 21122423 is 32422112.

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 21122423 - 2² = 21122419 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21122443) 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, 1508738 + ... + 1508751.

It is an arithmetic number, because the mean of its divisors is an integer number (6034980).

Almost surely, 2^21122423 is an apocalyptic number.

21122423 is a deficient number, since it is larger than the sum of its proper divisors (3017497).

21122423 is an equidigital number, since it uses as much as digits as its factorization.

21122423 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3017496.

The product of its digits is 192, while the sum is 17.

The square root of 21122423 is about 4595.9137285202. The cubic root of 21122423 is about 276.4274994752.

Adding to 21122423 its reverse (32422112), we get a palindrome (53544535).

The spelling of 21122423 in words is "twenty-one million, one hundred twenty-two thousand, four hundred twenty-three".