21706427 has 2 divisors, whose sum is σ = 21706428. Its totient is φ = 21706426.

The previous prime is 21706387. The next prime is 21706439. The reversal of 21706427 is 72460712.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21706427 - 2¹⁰ = 21705403 is a prime.

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 21706427.

It is not a weakly prime, because it can be changed into another prime (21703427) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10853213 + 10853214.

It is an arithmetic number, because the mean of its divisors is an integer number (10853214).

Almost surely, 2^21706427 is an apocalyptic number.

21706427 is a deficient number, since it is larger than the sum of its proper divisors (1).

21706427 is an equidigital number, since it uses as much as digits as its factorization.

21706427 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 4704, while the sum is 29.

The square root of 21706427 is about 4659.0156685721. The cubic root of 21706427 is about 278.9519793339.

The spelling of 21706427 in words is "twenty-one million, seven hundred six thousand, four hundred twenty-seven".