21305446 has 4 divisors (see below), whose sum is σ = 31958172. Its totient is φ = 10652722.

The previous prime is 21305423. The next prime is 21305461. The reversal of 21305446 is 64450312.

It is a semiprime because it is the product of two primes.

It is a self number, because there is not a number n which added to its sum of digits gives 21305446.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5326360 + ... + 5326363.

It is an arithmetic number, because the mean of its divisors is an integer number (7989543).

Almost surely, 2^21305446 is an apocalyptic number.

21305446 is a deficient number, since it is larger than the sum of its proper divisors (10652726).

21305446 is a wasteful number, since it uses less digits than its factorization.

21305446 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10652725.

The product of its (nonzero) digits is 2880, while the sum is 25.

The square root of 21305446 is about 4615.7822738946. The cubic root of 21305446 is about 277.2236070617.

Adding to 21305446 its reverse (64450312), we get a palindrome (85755758).

The spelling of 21305446 in words is "twenty-one million, three hundred five thousand, four hundred forty-six".