21308383 has 2 divisors, whose sum is σ = 21308384. Its totient is φ = 21308382.

The previous prime is 21308369. The next prime is 21308389. The reversal of 21308383 is 38380312.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21308383 - 2⁵ = 21308351 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21308389) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10654191 + 10654192.

It is an arithmetic number, because the mean of its divisors is an integer number (10654192).

Almost surely, 2^21308383 is an apocalyptic number.

21308383 is a deficient number, since it is larger than the sum of its proper divisors (1).

21308383 is an equidigital number, since it uses as much as digits as its factorization.

21308383 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3456, while the sum is 28.

The square root of 21308383 is about 4616.1004105197. The cubic root of 21308383 is about 277.2363450932.

Adding to 21308383 its reverse (38380312), we get a palindrome (59688695).

The spelling of 21308383 in words is "twenty-one million, three hundred eight thousand, three hundred eighty-three".