21610243 has 4 divisors (see below), whose sum is σ = 21768120. Its totient is φ = 21452368.

The previous prime is 21610241. The next prime is 21610279. The reversal of 21610243 is 34201612.

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 21610243 - 2¹ = 21610241 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21610243.

It is not an unprimeable number, because it can be changed into a prime (21610241) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 78733 + ... + 79006.

It is an arithmetic number, because the mean of its divisors is an integer number (5442030).

Almost surely, 2^21610243 is an apocalyptic number.

21610243 is a deficient number, since it is larger than the sum of its proper divisors (157877).

21610243 is a wasteful number, since it uses less digits than its factorization.

21610243 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 157876.

The product of its (nonzero) digits is 288, while the sum is 19.

The square root of 21610243 is about 4648.6818561825. The cubic root of 21610243 is about 278.5393450919.

Adding to 21610243 its reverse (34201612), we get a palindrome (55811855).

The spelling of 21610243 in words is "twenty-one million, six hundred ten thousand, two hundred forty-three".