21840053 has 4 divisors (see below), whose sum is σ = 23124780. Its totient is φ = 20555328.

The previous prime is 21840047. The next prime is 21840061. The reversal of 21840053 is 35004812.

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 11035684 + 10804369 = 3322^2 + 3287^2 .

It is a cyclic number.

It is not a de Polignac number, because 21840053 - 2⁶ = 21839989 is a prime.

It is a super-3 number, since 3×21840053³ (a number of 23 digits) contains 333 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21840023) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 642338 + ... + 642371.

It is an arithmetic number, because the mean of its divisors is an integer number (5781195).

Almost surely, 2^21840053 is an apocalyptic number.

It is an amenable number.

21840053 is a deficient number, since it is larger than the sum of its proper divisors (1284727).

21840053 is a wasteful number, since it uses less digits than its factorization.

21840053 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1284726.

The product of its (nonzero) digits is 960, while the sum is 23.

The square root of 21840053 is about 4673.3342486923. The cubic root of 21840053 is about 279.5232234824.

Adding to 21840053 its reverse (35004812), we get a palindrome (56844865).

The spelling of 21840053 in words is "twenty-one million, eight hundred forty thousand, fifty-three".