21123353 has 4 divisors (see below), whose sum is σ = 21412788. Its totient is φ = 20833920.

The previous prime is 21123331. The next prime is 21123359. The reversal of 21123353 is 35332112.

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 16908544 + 4214809 = 4112^2 + 2053^2 .

It is a cyclic number.

It is not a de Polignac number, because 21123353 - 2¹² = 21119257 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21123359) 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, 144608 + ... + 144753.

It is an arithmetic number, because the mean of its divisors is an integer number (5353197).

Almost surely, 2^21123353 is an apocalyptic number.

It is an amenable number.

21123353 is a deficient number, since it is larger than the sum of its proper divisors (289435).

21123353 is an equidigital number, since it uses as much as digits as its factorization.

21123353 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 289434.

The product of its digits is 540, while the sum is 20.

The square root of 21123353 is about 4596.0149042404. The cubic root of 21123353 is about 276.4315563614.

Adding to 21123353 its reverse (35332112), we get a palindrome (56455465).

The spelling of 21123353 in words is "twenty-one million, one hundred twenty-three thousand, three hundred fifty-three".