21840113 has 4 divisors (see below), whose sum is σ = 21979380. Its totient is φ = 21700848.

The previous prime is 21840109. The next prime is 21840131. The reversal of 21840113 is 31104812.

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 14348944 + 7491169 = 3788^2 + 2737^2 .

It is a cyclic number.

It is not a de Polignac number, because 21840113 - 2² = 21840109 is a prime.

It is a Duffinian number.

It is a plaindrome in base 11.

It is not an unprimeable number, because it can be changed into a prime (21840193) 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, 69398 + ... + 69711.

It is an arithmetic number, because the mean of its divisors is an integer number (5494845).

Almost surely, 2^21840113 is an apocalyptic number.

It is an amenable number.

21840113 is a deficient number, since it is larger than the sum of its proper divisors (139267).

21840113 is a wasteful number, since it uses less digits than its factorization.

21840113 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 139266.

The product of its (nonzero) digits is 192, while the sum is 20.

The square root of 21840113 is about 4673.3406680874. The cubic root of 21840113 is about 279.5234794552.

Adding to 21840113 its reverse (31104812), we get a palindrome (52944925).

The spelling of 21840113 in words is "twenty-one million, eight hundred forty thousand, one hundred thirteen".