21704219 has 4 divisors (see below), whose sum is σ = 21794520. Its totient is φ = 21613920.

The previous prime is 21704197. The next prime is 21704231. The reversal of 21704219 is 91240712.

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 21704219 - 2¹² = 21700123 is a prime.

It is a super-2 number, since 2×21704219² = 942146244799922, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21704279) 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, 44789 + ... + 45270.

It is an arithmetic number, because the mean of its divisors is an integer number (5448630).

Almost surely, 2^21704219 is an apocalyptic number.

21704219 is a deficient number, since it is larger than the sum of its proper divisors (90301).

21704219 is an equidigital number, since it uses as much as digits as its factorization.

21704219 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 90300.

The product of its (nonzero) digits is 1008, while the sum is 26.

The square root of 21704219 is about 4658.7787026215. The cubic root of 21704219 is about 278.9425205862.

The spelling of 21704219 in words is "twenty-one million, seven hundred four thousand, two hundred nineteen".