21905593 has 2 divisors, whose sum is σ = 21905594. Its totient is φ = 21905592.

The previous prime is 21905581. The next prime is 21905617. The reversal of 21905593 is 39550912.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 10969344 + 10936249 = 3312^2 + 3307^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21905593 is a prime.

It is not a weakly prime, because it can be changed into another prime (21905573) 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, 10952796 + 10952797.

It is an arithmetic number, because the mean of its divisors is an integer number (10952797).

Almost surely, 2^21905593 is an apocalyptic number.

It is an amenable number.

21905593 is a deficient number, since it is larger than the sum of its proper divisors (1).

21905593 is an equidigital number, since it uses as much as digits as its factorization.

21905593 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 12150, while the sum is 34.

The square root of 21905593 is about 4680.3411200467. The cubic root of 21905593 is about 279.8025521247.

The spelling of 21905593 in words is "twenty-one million, nine hundred five thousand, five hundred ninety-three".