21794609 has 2 divisors, whose sum is σ = 21794610. Its totient is φ = 21794608.

The previous prime is 21794557. The next prime is 21794611. The reversal of 21794609 is 90649712.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17405584 + 4389025 = 4172^2 + 2095^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21794609 is a prime.

Together with 21794611, 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 (21790609) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10897304 + 10897305.

It is an arithmetic number, because the mean of its divisors is an integer number (10897305).

Almost surely, 2^21794609 is an apocalyptic number.

It is an amenable number.

21794609 is a deficient number, since it is larger than the sum of its proper divisors (1).

21794609 is an equidigital number, since it uses as much as digits as its factorization.

21794609 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 27216, while the sum is 38.

The square root of 21794609 is about 4668.4696636050. The cubic root of 21794609 is about 279.3292148877.

The spelling of 21794609 in words is "twenty-one million, seven hundred ninety-four thousand, six hundred nine".