21042097 has 2 divisors, whose sum is σ = 21042098. Its totient is φ = 21042096.

The previous prime is 21042089. The next prime is 21042103. The reversal of 21042097 is 79024012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 10699441 + 10342656 = 3271^2 + 3216^2 .

It is a cyclic number.

It is not a de Polignac number, because 21042097 - 2³ = 21042089 is a prime.

It is not a weakly prime, because it can be changed into another prime (21042017) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10521048 + 10521049.

It is an arithmetic number, because the mean of its divisors is an integer number (10521049).

Almost surely, 2^21042097 is an apocalyptic number.

It is an amenable number.

21042097 is a deficient number, since it is larger than the sum of its proper divisors (1).

21042097 is an equidigital number, since it uses as much as digits as its factorization.

21042097 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1008, while the sum is 25.

The square root of 21042097 is about 4587.1665546391. The cubic root of 21042097 is about 276.0766476544.

The spelling of 21042097 in words is "twenty-one million, forty-two thousand, ninety-seven".