21310305 has 32 divisors (see below), whose sum is σ = 37463040. Its totient is φ = 10296000.

The previous prime is 21310301. The next prime is 21310309. The reversal of 21310305 is 50301312.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21310301) and next prime (21310309).

It is not a de Polignac number, because 21310305 - 2² = 21310301 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is not an unprimeable number, because it can be changed into a prime (21310301) 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 31 ways as a sum of consecutive naturals, for example, 4930 + ... + 8180.

It is an arithmetic number, because the mean of its divisors is an integer number (1170720).

Almost surely, 2^21310305 is an apocalyptic number.

It is an amenable number.

21310305 is a deficient number, since it is larger than the sum of its proper divisors (16152735).

21310305 is a wasteful number, since it uses less digits than its factorization.

21310305 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3301.

The product of its (nonzero) digits is 90, while the sum is 15.

The square root of 21310305 is about 4616.3085902049. The cubic root of 21310305 is about 277.2446803453.

Adding to 21310305 its reverse (50301312), we get a palindrome (71611617).

The spelling of 21310305 in words is "twenty-one million, three hundred ten thousand, three hundred five".