21303407 has 2 divisors, whose sum is σ = 21303408. Its totient is φ = 21303406.

The previous prime is 21303349. The next prime is 21303409. The reversal of 21303407 is 70430312.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21303407 - 2¹⁸ = 21041263 is a prime.

Together with 21303409, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21303409) 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 as a sum of consecutive naturals, namely, 10651703 + 10651704.

It is an arithmetic number, because the mean of its divisors is an integer number (10651704).

Almost surely, 2^21303407 is an apocalyptic number.

21303407 is a deficient number, since it is larger than the sum of its proper divisors (1).

21303407 is an equidigital number, since it uses as much as digits as its factorization.

21303407 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 504, while the sum is 20.

The square root of 21303407 is about 4615.5613959734. The cubic root of 21303407 is about 277.2147630481.

Adding to 21303407 its reverse (70430312), we get a palindrome (91733719).

The spelling of 21303407 in words is "twenty-one million, three hundred three thousand, four hundred seven".