21193217 has 2 divisors, whose sum is σ = 21193218. Its totient is φ = 21193216.

The previous prime is 21193201. The next prime is 21193223. The reversal of 21193217 is 71239112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18931201 + 2262016 = 4351^2 + 1504^2 .

It is a cyclic number.

It is not a de Polignac number, because 21193217 - 2⁴ = 21193201 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21193247) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10596608 + 10596609.

It is an arithmetic number, because the mean of its divisors is an integer number (10596609).

Almost surely, 2^21193217 is an apocalyptic number.

It is an amenable number.

21193217 is a deficient number, since it is larger than the sum of its proper divisors (1).

21193217 is an equidigital number, since it uses as much as digits as its factorization.

21193217 is an evil number, because the sum of its binary digits is even.

The product of its digits is 756, while the sum is 26.

The square root of 21193217 is about 4603.6091276302. The cubic root of 21193217 is about 276.7359802785.

The spelling of 21193217 in words is "twenty-one million, one hundred ninety-three thousand, two hundred seventeen".