21665383 has 2 divisors, whose sum is σ = 21665384. Its totient is φ = 21665382.

The previous prime is 21665363. The next prime is 21665389. The reversal of 21665383 is 38356612.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21665383 - 2⁵ = 21665351 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21665389) 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, 10832691 + 10832692.

It is an arithmetic number, because the mean of its divisors is an integer number (10832692).

Almost surely, 2^21665383 is an apocalyptic number.

21665383 is a deficient number, since it is larger than the sum of its proper divisors (1).

21665383 is an equidigital number, since it uses as much as digits as its factorization.

21665383 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 25920, while the sum is 34.

The square root of 21665383 is about 4654.6087912949. The cubic root of 21665383 is about 278.7760478920.

The spelling of 21665383 in words is "twenty-one million, six hundred sixty-five thousand, three hundred eighty-three".