21305315 has 8 divisors (see below), whose sum is σ = 25640928. Its totient is φ = 16994560.

The previous prime is 21305309. The next prime is 21305321. The reversal of 21305315 is 51350312.

It is an interprime number because it is at equal distance from previous prime (21305309) and next prime (21305321).

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

It is not a de Polignac number, because 21305315 - 2⁸ = 21305059 is a prime.

It is a Duffinian number.

It is an unprimeable number.

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, 4271 + ... + 7800.

It is an arithmetic number, because the mean of its divisors is an integer number (3205116).

Almost surely, 2^21305315 is an apocalyptic number.

21305315 is a deficient number, since it is larger than the sum of its proper divisors (4335613).

21305315 is a wasteful number, since it uses less digits than its factorization.

21305315 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12429.

The product of its (nonzero) digits is 450, while the sum is 20.

The square root of 21305315 is about 4615.7680834288. The cubic root of 21305315 is about 277.2230388758.

Adding to 21305315 its reverse (51350312), we get a palindrome (72655627).

The spelling of 21305315 in words is "twenty-one million, three hundred five thousand, three hundred fifteen".