21306963 has 4 divisors (see below), whose sum is σ = 28409288. Its totient is φ = 14204640.

The previous prime is 21306953. The next prime is 21306979. The reversal of 21306963 is 36960312.

It is a happy number.

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

It is not a de Polignac number, because 21306963 - 2⁸ = 21306707 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 21306963.

It is not an unprimeable number, because it can be changed into a prime (21306913) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3551158 + ... + 3551163.

It is an arithmetic number, because the mean of its divisors is an integer number (7102322).

Almost surely, 2^21306963 is an apocalyptic number.

21306963 is a deficient number, since it is larger than the sum of its proper divisors (7102325).

21306963 is an equidigital number, since it uses as much as digits as its factorization.

21306963 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7102324.

The product of its (nonzero) digits is 5832, while the sum is 30.

The square root of 21306963 is about 4615.9465984779. The cubic root of 21306963 is about 277.2301865725.

The spelling of 21306963 in words is "twenty-one million, three hundred six thousand, nine hundred sixty-three".