21405383 has 2 divisors, whose sum is σ = 21405384. Its totient is φ = 21405382.

The previous prime is 21405367. The next prime is 21405401. The reversal of 21405383 is 38350412.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21405383 - 2⁴ = 21405367 is a prime.

It is a Sophie Germain prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21405313) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10702691 + 10702692.

It is an arithmetic number, because the mean of its divisors is an integer number (10702692).

Almost surely, 2^21405383 is an apocalyptic number.

21405383 is a deficient number, since it is larger than the sum of its proper divisors (1).

21405383 is an equidigital number, since it uses as much as digits as its factorization.

21405383 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2880, while the sum is 26.

The square root of 21405383 is about 4626.5951843661. The cubic root of 21405383 is about 277.6563867041.

Adding to 21405383 its reverse (38350412), we get a palindrome (59755795).

The spelling of 21405383 in words is "twenty-one million, four hundred five thousand, three hundred eighty-three".