21423403 has 2 divisors, whose sum is σ = 21423404. Its totient is φ = 21423402.

The previous prime is 21423377. The next prime is 21423421. The reversal of 21423403 is 30432412.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21423403 - 2⁵ = 21423371 is a prime.

It is a super-2 number, since 2×21423403² = 917924392200818, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21420403) 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 as a sum of consecutive naturals, namely, 10711701 + 10711702.

It is an arithmetic number, because the mean of its divisors is an integer number (10711702).

Almost surely, 2^21423403 is an apocalyptic number.

21423403 is a deficient number, since it is larger than the sum of its proper divisors (1).

21423403 is an equidigital number, since it uses as much as digits as its factorization.

21423403 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 576, while the sum is 19.

The square root of 21423403 is about 4628.5422111071. The cubic root of 21423403 is about 277.7342793339.

Adding to 21423403 its reverse (30432412), we get a palindrome (51855815).

Subtracting 21423403 from its reverse (30432412), we obtain a palindrome (9009009).

The spelling of 21423403 in words is "twenty-one million, four hundred twenty-three thousand, four hundred three".