21919305 has 8 divisors (see below), whose sum is σ = 35070912. Its totient is φ = 11690288.

The previous prime is 21919283. The next prime is 21919309. The reversal of 21919305 is 50391912.

21919305 = 1095² + 1096² + ... + 1112².

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

It is a cyclic number.

It is not a de Polignac number, because 21919305 - 2¹² = 21915209 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21919309) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 730629 + ... + 730658.

It is an arithmetic number, because the mean of its divisors is an integer number (4383864).

Almost surely, 2^21919305 is an apocalyptic number.

It is an amenable number.

21919305 is a deficient number, since it is larger than the sum of its proper divisors (13151607).

21919305 is a wasteful number, since it uses less digits than its factorization.

21919305 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1461295.

The product of its (nonzero) digits is 2430, while the sum is 30.

The square root of 21919305 is about 4681.8057413780. The cubic root of 21919305 is about 279.8609215762.

The spelling of 21919305 in words is "twenty-one million, nine hundred nineteen thousand, three hundred five".