21223403 has 2 divisors, whose sum is σ = 21223404. Its totient is φ = 21223402.

The previous prime is 21223393. The next prime is 21223409. The reversal of 21223403 is 30432212.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21223403 - 2⁴ = 21223387 is a prime.

It is not a weakly prime, because it can be changed into another prime (21223409) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10611701 + 10611702.

It is an arithmetic number, because the mean of its divisors is an integer number (10611702).

Almost surely, 2^21223403 is an apocalyptic number.

21223403 is a deficient number, since it is larger than the sum of its proper divisors (1).

21223403 is an equidigital number, since it uses as much as digits as its factorization.

21223403 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 288, while the sum is 17.

The square root of 21223403 is about 4606.8864757013. The cubic root of 21223403 is about 276.8673051482.

Adding to 21223403 its reverse (30432212), we get a palindrome (51655615).

The spelling of 21223403 in words is "twenty-one million, two hundred twenty-three thousand, four hundred three".