21219505 has 8 divisors (see below), whose sum is σ = 25501824. Its totient is φ = 16950000.

The previous prime is 21219493. The next prime is 21219529. The reversal of 21219505 is 50591212.

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

It is not a de Polignac number, because 21219505 - 2⁷ = 21219377 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21219505.

It is an unprimeable number.

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, 930 + ... + 6580.

It is an arithmetic number, because the mean of its divisors is an integer number (3187728).

Almost surely, 2^21219505 is an apocalyptic number.

It is an amenable number.

21219505 is a deficient number, since it is larger than the sum of its proper divisors (4282319).

21219505 is an equidigital number, since it uses as much as digits as its factorization.

21219505 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6407.

The product of its (nonzero) digits is 900, while the sum is 25.

The square root of 21219505 is about 4606.4633939716. The cubic root of 21219505 is about 276.8503538165.

The spelling of 21219505 in words is "twenty-one million, two hundred nineteen thousand, five hundred five".