21000193 has 2 divisors, whose sum is σ = 21000194. Its totient is φ = 21000192.

The previous prime is 21000191. The next prime is 21000229. The reversal of 21000193 is 39100012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17032129 + 3968064 = 4127^2 + 1992^2 .

It is a cyclic number.

It is not a de Polignac number, because 21000193 - 2¹ = 21000191 is a prime.

Together with 21000191, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (21000191) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10500096 + 10500097.

It is an arithmetic number, because the mean of its divisors is an integer number (10500097).

Almost surely, 2^21000193 is an apocalyptic number.

It is an amenable number.

21000193 is a deficient number, since it is larger than the sum of its proper divisors (1).

21000193 is an equidigital number, since it uses as much as digits as its factorization.

21000193 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 54, while the sum is 16.

The square root of 21000193 is about 4582.5967529339. The cubic root of 21000193 is about 275.8932628298.

The spelling of 21000193 in words is "twenty-one million, one hundred ninety-three", and thus it is an aban number.