21608143 has 4 divisors (see below), whose sum is σ = 21622408. Its totient is φ = 21593880.

The previous prime is 21608123. The next prime is 21608227. The reversal of 21608143 is 34180612.

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 21608143 - 2¹³ = 21599951 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21608113) 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, 4548 + ... + 7993.

It is an arithmetic number, because the mean of its divisors is an integer number (5405602).

Almost surely, 2^21608143 is an apocalyptic number.

21608143 is a deficient number, since it is larger than the sum of its proper divisors (14265).

21608143 is a wasteful number, since it uses less digits than its factorization.

21608143 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14264.

The product of its (nonzero) digits is 1152, while the sum is 25.

The square root of 21608143 is about 4648.4559802154. The cubic root of 21608143 is about 278.5303223401.

Adding to 21608143 its reverse (34180612), we get a palindrome (55788755).

The spelling of 21608143 in words is "twenty-one million, six hundred eight thousand, one hundred forty-three".