21365593 has 2 divisors, whose sum is σ = 21365594. Its totient is φ = 21365592.

The previous prime is 21365579. The next prime is 21365609. The reversal of 21365593 is 39556312.

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., 18636489 + 2729104 = 4317^2 + 1652^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21365593 is a prime.

It is not a weakly prime, because it can be changed into another prime (21365543) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10682796 + 10682797.

It is an arithmetic number, because the mean of its divisors is an integer number (10682797).

Almost surely, 2^21365593 is an apocalyptic number.

It is an amenable number.

21365593 is a deficient number, since it is larger than the sum of its proper divisors (1).

21365593 is an equidigital number, since it uses as much as digits as its factorization.

21365593 is an evil number, because the sum of its binary digits is even.

The product of its digits is 24300, while the sum is 34.

The square root of 21365593 is about 4622.2930456647. The cubic root of 21365593 is about 277.4842368559.

The spelling of 21365593 in words is "twenty-one million, three hundred sixty-five thousand, five hundred ninety-three".