21845897 has 2 divisors, whose sum is σ = 21845898. Its totient is φ = 21845896.

The previous prime is 21845893. The next prime is 21845899. The reversal of 21845897 is 79854812.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17606416 + 4239481 = 4196^2 + 2059^2 .

It is a cyclic number.

It is not a de Polignac number, because 21845897 - 2² = 21845893 is a prime.

Together with 21845899, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21845893) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10922948 + 10922949.

It is an arithmetic number, because the mean of its divisors is an integer number (10922949).

Almost surely, 2^21845897 is an apocalyptic number.

It is an amenable number.

21845897 is a deficient number, since it is larger than the sum of its proper divisors (1).

21845897 is an equidigital number, since it uses as much as digits as its factorization.

21845897 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 161280, while the sum is 44.

The square root of 21845897 is about 4673.9594563924. The cubic root of 21845897 is about 279.5481530318.

The spelling of 21845897 in words is "twenty-one million, eight hundred forty-five thousand, eight hundred ninety-seven".