21608893 has 2 divisors, whose sum is σ = 21608894. Its totient is φ = 21608892.

The previous prime is 21608837. The next prime is 21608903. The reversal of 21608893 is 39880612.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20403289 + 1205604 = 4517^2 + 1098^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21608893 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21608693) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10804446 + 10804447.

It is an arithmetic number, because the mean of its divisors is an integer number (10804447).

Almost surely, 2^21608893 is an apocalyptic number.

It is an amenable number.

21608893 is a deficient number, since it is larger than the sum of its proper divisors (1).

21608893 is an equidigital number, since it uses as much as digits as its factorization.

21608893 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 20736, while the sum is 37.

The square root of 21608893 is about 4648.5366514636. The cubic root of 21608893 is about 278.5335448186.

The spelling of 21608893 in words is "twenty-one million, six hundred eight thousand, eight hundred ninety-three".