21608267 has 4 divisors (see below), whose sum is σ = 21818160. Its totient is φ = 21398376.

The previous prime is 21608239. The next prime is 21608273. The reversal of 21608267 is 76280612.

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

It is a cyclic number.

It is not a de Polignac number, because 21608267 - 2¹⁸ = 21346123 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21608227) 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, 104792 + ... + 104997.

It is an arithmetic number, because the mean of its divisors is an integer number (5454540).

Almost surely, 2^21608267 is an apocalyptic number.

21608267 is a deficient number, since it is larger than the sum of its proper divisors (209893).

21608267 is a wasteful number, since it uses less digits than its factorization.

21608267 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 209892.

The product of its (nonzero) digits is 8064, while the sum is 32.

The square root of 21608267 is about 4648.4693179583. The cubic root of 21608267 is about 278.5308551284.

Adding to 21608267 its reverse (76280612), we get a palindrome (97888879).

The spelling of 21608267 in words is "twenty-one million, six hundred eight thousand, two hundred sixty-seven".