21308063 has 16 divisors (see below), whose sum is σ = 25827840. Its totient is φ = 17172000.

The previous prime is 21308059. The next prime is 21308081. The reversal of 21308063 is 36080312.

It is a cyclic number.

It is not a de Polignac number, because 21308063 - 2² = 21308059 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21308003) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 19553 + ... + 20613.

It is an arithmetic number, because the mean of its divisors is an integer number (1614240).

Almost surely, 2^21308063 is an apocalyptic number.

21308063 is a deficient number, since it is larger than the sum of its proper divisors (4519777).

21308063 is a wasteful number, since it uses less digits than its factorization.

21308063 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1238.

The product of its (nonzero) digits is 864, while the sum is 23.

The square root of 21308063 is about 4616.0657490985. The cubic root of 21308063 is about 277.2349572814.

Adding to 21308063 its reverse (36080312), we get a palindrome (57388375).

The spelling of 21308063 in words is "twenty-one million, three hundred eight thousand, sixty-three".