21704671 has 2 divisors, whose sum is σ = 21704672. Its totient is φ = 21704670.

The previous prime is 21704653. The next prime is 21704677. The reversal of 21704671 is 17640712.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21704671 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21704677) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10852335 + 10852336.

It is an arithmetic number, because the mean of its divisors is an integer number (10852336).

Almost surely, 2^21704671 is an apocalyptic number.

21704671 is a deficient number, since it is larger than the sum of its proper divisors (1).

21704671 is an equidigital number, since it uses as much as digits as its factorization.

21704671 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2352, while the sum is 28.

The square root of 21704671 is about 4658.8272129367. The cubic root of 21704671 is about 278.9444569400.

The spelling of 21704671 in words is "twenty-one million, seven hundred four thousand, six hundred seventy-one".