21819005 has 16 divisors (see below), whose sum is σ = 28479360. Its totient is φ = 15951168.

The previous prime is 21819001. The next prime is 21819059. The reversal of 21819005 is 50091812.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 21819005 - 2² = 21819001 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21819001) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5066 + ... + 8324.

It is an arithmetic number, because the mean of its divisors is an integer number (1779960).

Almost surely, 2^21819005 is an apocalyptic number.

It is an amenable number.

21819005 is a deficient number, since it is larger than the sum of its proper divisors (6660355).

21819005 is a wasteful number, since it uses less digits than its factorization.

21819005 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3380.

The product of its (nonzero) digits is 720, while the sum is 26.

The square root of 21819005 is about 4671.0817804873. The cubic root of 21819005 is about 279.4333992829.

The spelling of 21819005 in words is "twenty-one million, eight hundred nineteen thousand, five".