21459197 has 2 divisors, whose sum is σ = 21459198. Its totient is φ = 21459196.

The previous prime is 21459187. The next prime is 21459199. The reversal of 21459197 is 79195412.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 13697401 + 7761796 = 3701^2 + 2786^2 .

It is a cyclic number.

It is not a de Polignac number, because 21459197 - 2⁴ = 21459181 is a prime.

Together with 21459199, it forms a pair of twin primes.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21459197.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21459199) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10729598 + 10729599.

It is an arithmetic number, because the mean of its divisors is an integer number (10729599).

Almost surely, 2^21459197 is an apocalyptic number.

It is an amenable number.

21459197 is a deficient number, since it is larger than the sum of its proper divisors (1).

21459197 is an equidigital number, since it uses as much as digits as its factorization.

21459197 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 22680, while the sum is 38.

The square root of 21459197 is about 4632.4072575714. The cubic root of 21459197 is about 277.8888717885. Note that the first 4 decimals are identical.

The spelling of 21459197 in words is "twenty-one million, four hundred fifty-nine thousand, one hundred ninety-seven".