21704919 has 4 divisors (see below), whose sum is σ = 28939896. Its totient is φ = 14469944.

The previous prime is 21704887. The next prime is 21704933. The reversal of 21704919 is 91940712.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21704919 - 2⁵ = 21704887 is a prime.

It is a super-2 number, since 2×21704919² = 942207017593122, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21704919.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21704999) 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 in 3 ways as a sum of consecutive naturals, for example, 3617484 + ... + 3617489.

It is an arithmetic number, because the mean of its divisors is an integer number (7234974).

Almost surely, 2^21704919 is an apocalyptic number.

21704919 is a deficient number, since it is larger than the sum of its proper divisors (7234977).

21704919 is an equidigital number, since it uses as much as digits as its factorization.

21704919 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7234976.

The product of its (nonzero) digits is 4536, while the sum is 33.

The square root of 21704919 is about 4658.8538290013. The cubic root of 21704919 is about 278.9455193528.

The spelling of 21704919 in words is "twenty-one million, seven hundred four thousand, nine hundred nineteen".