21819689 has 4 divisors (see below), whose sum is σ = 22145424. Its totient is φ = 21493956.

The previous prime is 21819683. The next prime is 21819713. The reversal of 21819689 is 98691812.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21819689 - 2⁴ = 21819673 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21819683) 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, 162767 + ... + 162900.

It is an arithmetic number, because the mean of its divisors is an integer number (5536356).

Almost surely, 2^21819689 is an apocalyptic number.

It is an amenable number.

21819689 is a deficient number, since it is larger than the sum of its proper divisors (325735).

21819689 is an equidigital number, since it uses as much as digits as its factorization.

21819689 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 325734.

The product of its digits is 62208, while the sum is 44.

The square root of 21819689 is about 4671.1549963580. The cubic root of 21819689 is about 279.4363192213.

The spelling of 21819689 in words is "twenty-one million, eight hundred nineteen thousand, six hundred eighty-nine".