21365963 has 8 divisors (see below), whose sum is σ = 21695040. Its totient is φ = 21039040.

The previous prime is 21365947. The next prime is 21365987. The reversal of 21365963 is 36956312.

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 21365963 - 2⁴ = 21365947 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21365933) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 38081 + ... + 38637.

It is an arithmetic number, because the mean of its divisors is an integer number (2711880).

Almost surely, 2^21365963 is an apocalyptic number.

21365963 is a deficient number, since it is larger than the sum of its proper divisors (329077).

21365963 is an equidigital number, since it uses as much as digits as its factorization.

21365963 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1077.

The product of its digits is 29160, while the sum is 35.

The square root of 21365963 is about 4622.3330689166. Note that the first 3 decimals coincide. The cubic root of 21365963 is about 277.4858386302.

The spelling of 21365963 in words is "twenty-one million, three hundred sixty-five thousand, nine hundred sixty-three".