21703819 has 4 divisors (see below), whose sum is σ = 21714696. Its totient is φ = 21692944.

The previous prime is 21703817. The next prime is 21703823. The reversal of 21703819 is 91830712.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 21703819 - 2¹ = 21703817 is a prime.

It is a super-2 number, since 2×21703819² = 942111518369522, which contains 22 as substring.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21703817) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1489 + ... + 6754.

It is an arithmetic number, because the mean of its divisors is an integer number (5428674).

Almost surely, 2^21703819 is an apocalyptic number.

21703819 is a deficient number, since it is larger than the sum of its proper divisors (10877).

21703819 is an equidigital number, since it uses as much as digits as its factorization.

21703819 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10876.

The product of its (nonzero) digits is 3024, while the sum is 31.

The square root of 21703819 is about 4658.7357727177. The cubic root of 21703819 is about 278.9408069763.

It can be divided in two parts, 21703 and 819, that added together give a palindrome (22522).

The spelling of 21703819 in words is "twenty-one million, seven hundred three thousand, eight hundred nineteen".