21308111 has 8 divisors (see below), whose sum is σ = 23365584. Its totient is φ = 19270720.

The previous prime is 21308107. The next prime is 21308137. The reversal of 21308111 is 11180312.

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 21308111 - 2² = 21308107 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21308111.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21308141) 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, 2750 + ... + 7083.

It is an arithmetic number, because the mean of its divisors is an integer number (2920698).

Almost surely, 2^21308111 is an apocalyptic number.

21308111 is a deficient number, since it is larger than the sum of its proper divisors (2057473).

21308111 is a wasteful number, since it uses less digits than its factorization.

21308111 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10041.

The product of its (nonzero) digits is 48, while the sum is 17.

The square root of 21308111 is about 4616.0709483282. The cubic root of 21308111 is about 277.2351654541.

Adding to 21308111 its reverse (11180312), we get a palindrome (32488423).

The spelling of 21308111 in words is "twenty-one million, three hundred eight thousand, one hundred eleven".