21166903 has 2 divisors, whose sum is σ = 21166904. Its totient is φ = 21166902.

The previous prime is 21166891. The next prime is 21166907. The reversal of 21166903 is 30966112.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21166903 is a prime.

It is a super-2 number, since 2×21166903² = 896075565222818, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21166907) by changing a digit.

It is a good prime.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10583451 + 10583452.

It is an arithmetic number, because the mean of its divisors is an integer number (10583452).

Almost surely, 2^21166903 is an apocalyptic number.

21166903 is a deficient number, since it is larger than the sum of its proper divisors (1).

21166903 is an equidigital number, since it uses as much as digits as its factorization.

21166903 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1944, while the sum is 28.

The square root of 21166903 is about 4600.7502649025. The cubic root of 21166903 is about 276.6213988614.

The spelling of 21166903 in words is "twenty-one million, one hundred sixty-six thousand, nine hundred three".