21220423 has 4 divisors (see below), whose sum is σ = 24251920. Its totient is φ = 18188928.

The previous prime is 21220417. The next prime is 21220429. The reversal of 21220423 is 32402212.

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

It is an interprime number because it is at equal distance from previous prime (21220417) and next prime (21220429).

It is a cyclic number.

It is not a de Polignac number, because 21220423 - 2⁵ = 21220391 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21220397 and 21220406.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21220429) 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, 1515738 + ... + 1515751.

It is an arithmetic number, because the mean of its divisors is an integer number (6062980).

Almost surely, 2^21220423 is an apocalyptic number.

21220423 is a deficient number, since it is larger than the sum of its proper divisors (3031497).

21220423 is an equidigital number, since it uses as much as digits as its factorization.

21220423 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3031496.

The product of its (nonzero) digits is 192, while the sum is 16.

The square root of 21220423 is about 4606.5630354962. The cubic root of 21220423 is about 276.8543461333.

Adding to 21220423 its reverse (32402212), we get a palindrome (53622635).

The spelling of 21220423 in words is "twenty-one million, two hundred twenty thousand, four hundred twenty-three".