21098191 has 2 divisors, whose sum is σ = 21098192. Its totient is φ = 21098190.

The previous prime is 21098183. The next prime is 21098201. The reversal of 21098191 is 19189012.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21098191 - 2³ = 21098183 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21098111) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10549095 + 10549096.

It is an arithmetic number, because the mean of its divisors is an integer number (10549096).

Almost surely, 2^21098191 is an apocalyptic number.

21098191 is a deficient number, since it is larger than the sum of its proper divisors (1).

21098191 is an equidigital number, since it uses as much as digits as its factorization.

21098191 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1296, while the sum is 31.

The square root of 21098191 is about 4593.2767171160. The cubic root of 21098191 is about 276.3217515961.

The spelling of 21098191 in words is "twenty-one million, ninety-eight thousand, one hundred ninety-one".