21019405 has 8 divisors (see below), whose sum is σ = 27516384. Its totient is φ = 15286800.

The previous prime is 21019393. The next prime is 21019409. The reversal of 21019405 is 50491012.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21019405 - 2⁵ = 21019373 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21019409) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 191031 + ... + 191140.

It is an arithmetic number, because the mean of its divisors is an integer number (3439548).

Almost surely, 2^21019405 is an apocalyptic number.

It is an amenable number.

21019405 is a deficient number, since it is larger than the sum of its proper divisors (6496979).

21019405 is a wasteful number, since it uses less digits than its factorization.

21019405 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 382187.

The product of its (nonzero) digits is 360, while the sum is 22.

The square root of 21019405 is about 4584.6924651497. The cubic root of 21019405 is about 275.9773707205.

The spelling of 21019405 in words is "twenty-one million, nineteen thousand, four hundred five".