21109153 has 4 divisors (see below), whose sum is σ = 22732948. Its totient is φ = 19485360.

The previous prime is 21109139. The next prime is 21109159. The reversal of 21109153 is 35190112.

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

It can be written as a sum of positive squares in 2 ways, for example, as 12306064 + 8803089 = 3508^2 + 2967^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21109153 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21109159) 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, 811878 + ... + 811903.

It is an arithmetic number, because the mean of its divisors is an integer number (5683237).

Almost surely, 2^21109153 is an apocalyptic number.

It is an amenable number.

21109153 is a deficient number, since it is larger than the sum of its proper divisors (1623795).

21109153 is a wasteful number, since it uses less digits than its factorization.

21109153 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1623794.

The product of its (nonzero) digits is 270, while the sum is 22.

The square root of 21109153 is about 4594.4698279562. The cubic root of 21109153 is about 276.3695995307.

Adding to 21109153 its reverse (35190112), we get a palindrome (56299265).

The spelling of 21109153 in words is "twenty-one million, one hundred nine thousand, one hundred fifty-three".